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Parent Category: Products

Category: Headphone Measurements

Created: 10 December 2022

Reviewed on: SoundStage! Solo, December 2022

I measured the Sivga Oriole headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Orioles’ frequency response, which shows some weird stuff. That dip centered near 200Hz looks scary, especially considering that it’s about an octave wide, although I should note that response dips are less audible than peaks, if the magnitude and Q are comparable. However, above about 500Hz, they’re not very far off the Harman curve—but there’s a lot less energy below 500Hz than the Harman curve recommends.

Here we can see the difference in the Orioles’ response when a high-impedance (75 ohms) source is substituted for a typical low-impedance source (5 ohms). It’s just a 1dB bump in the bass with the high-impedance source, which would be at most barely noticeable.

This chart shows the Orioles’ right-channel response compared with the open-back Sivga P-IIs, the HiFiMan Sundara Closed-Backs, and the AKG K371s (one of the headphones said to come closest to the Harman curve). All are normalized to 94dB at 500Hz. Clearly, the Orioles are outside the norm in some ways.

The Orioles’ spectral decay—i.e., resonance plot—shows a pretty strong resonance centered at about 500Hz, but it’s got a very high Q (i.e., narrow bandwidth), so I doubt it’ll be very noticeable. There’s another resonance centered at about 4kHz; it’s better-damped, but it might result in a slightly bright sound at times.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA, both levels set with pink noise. There’s some observable distortion in the bass at very high levels, and certainly more than you’d likely get with a planar-magnetic driver. But considering that it’s only about 2% THD at the loud level of 90dBA, I doubt it’d be audible.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The Orioles’ isolation is excellent, delivering what should be an audibly quieter experience than the other two closed-back models included in this chart. I threw in the Sivga P-II headphones so you could see how an open-back design compares.

The impedance of the Orioles is nearly flat at about 35 ohms through most of the audio range, with a rise and corresponding phase-response wrinkle centered at 45Hz, which is typical of a dynamic driver. That rise is the cause of the difference in frequency response when the Orioles are used with a high-impedance source, but considering that it’s only about a 1dB bump in the bass, it’s nothing to be concerned about.

Sensitivity of the Orioles, calculated for 32 ohms rated impedance and averaged from 300Hz to 3kHz, is 106.8dB with a 1mW signal, which is plenty high enough that any source device should be able to drive these headphones to loud levels.

Bottom line: The Oriole headphones’ engineering looks solid, and you can certainly drive them with any conceivable source device. However, the frequency response is idiosyncratic. Whether you’ll dig it, I can’t say, but I’d recommend you hear them before you buy, or buy them from a merchant that accepts returns.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 December 2022

Reviewed on: SoundStage! Solo, December 2022

I measured the Linsoul 7Hz Timeless earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The earphones were amplified using a Musical Fidelity V-CAN amplifier. Except as noted, I used the supplied medium-sized silicone tips for all measurements because they fit best in the ear simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the 7Hz Timelesses’ frequency response. This is fairly normal for earphones, with a few exceptions. There seems to be a bit of excess upper bass, and the 3kHz peak, while common, is unusually narrow in bandwidth. Also, there’s less energy in the mid-treble (around 7kHz) than we might normally see, but more energy above 10kHz than is normal for earphones. I can’t really speculate as to what this combination will sound like—maybe a little “smiley” (i.e., bass- and treble-boosted)?

This chart shows how the 7Hz Timelesses’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. There’s a very tiny, and inaudible, bass boost below 30Hz.

This chart shows the 7Hz Timelesses’ right-channel response compared with various earphones, including the AKG N5005s, which are said to be the passive earphones that come closest to the Harman curve. Basically, the variations from what’s more or less “normal” for earphones are as I described above.

The 7Hz Timelesses’ spectral-decay plot looks clean; that peak at around 3kHz corresponds with the earphones’ response peak at that frequency, and it’s very well-damped and won’t be audible as a resonance.

The distortion we see with the 7Hz Timeless earphones is much less than we normally see from earphones with dynamic drivers or balanced armatures—but comparable to what we usually see from planar-magnetic headphones.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. In the 43AG ear/cheek simulator, the 7Hz Timelesses offer less isolation than most earphones do; I imagine that’s because their large size prevents them from filling the ear as completely as most earphones can.

The impedance curve of the 7Hz Timelesses is dead flat at 14 ohms, which is typical for planar-magnetic drivers. The phase response is also flat.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 14.8 ohms rated impedance, is 99.2dB. That’s low for earphones, but still high enough that the 7Hz Timelesses should play reasonably loud from almost any source device.

Bottom line: Looks like pretty solid engineering here, with high-quality drivers. There are some frequency-response anomalies; I’m eager to find out what Geoff Morrison heard.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 November 2022

Reviewed on: SoundStage! Solo, November 2022

I measured the HiFiMan Sundara Closed-Back headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

Well, this is weird. This chart shows the Sundara Closed-Backs’ frequency response, which looks a lot more idiosyncratic than I expected. There’s a strange bump around 300Hz (the source of the extra upper-bass energy I heard), and then an unusual midrange bump centered at about 1.3kHz. There’s a lot of treble energy, although probably not enough to make these headphones sound overtly bright.

Here we can see the difference in the headphones’ response when a high-impedance (75 ohms) source is substituted for a typical low-impedance source (5 ohms). As usual with planar-magnetic headphones, there’s no significant difference, so these headphones’ response will not change significantly when you switch to a different source device.

This chart shows the Sundara Closed-Backs’ right-channel response compared with the open-back Sundaras, the Focal Celestees, and AKG K371 closed-back headphones (the K371s are one of the headphones noted for coming closest to the Harman curve). All are normalized to 94dB at 500Hz. Clearly, the Sundara Closed-Backs have more lower- and mid-midrange energy than the other headphones, more energy around 5 to 7kHz, and less energy in the 3kHz range. Frankly, I’m surprised they sound as normal as they do.

The Sundara Closed-Backs’ spectral decay—i.e., resonance plot—has the usual “hash” we see with planar-magnetic models. This doesn’t present itself as a coloration, per se, but it does seem to enhance the sense of space. Normally I might expect to see a broad hash band between 2 and 5kHz, but here, we see narrower hash bands instead, one centered at about 3.5kHz, the other spanning the range between 6 and 9kHz.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA, both levels set with pink noise. With most planar-magnetics, these lines show near-zero distortion, but with these, we see a distortion peak that corresponds with that frequency-response anomaly around 300Hz, and more distortion peaks that correspond with the high-frequency hash bands we saw in the previous measurement.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The Sundara Closed-Backs’ isolation is more or less in the range of other closed-back models. I also included the HiFiMan HE400se headphones, so you can see how an open-back model compares.

The impedance of the Sundara Closed-Backs is essentially flat at 19 ohms, with a correspondingly flat phase response—par for the course with planar-magnetics.

Sensitivity of the Sundara Closed-Backs, calculated for 20 ohms impedance and averaged from 300Hz to 3kHz, is 93.2dB with a 1mW signal, a little lower than rated, but I do this measurement differently than the industry standard, which measures only a 500Hz tone.

Bottom line: It’s hard to ignore the Sundara Closed-Back headphones’ idiosyncratic frequency response. I liked them a lot, but I’d suggest you give them a listen yourself before you buy, if possible.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 November 2022

Reviewed on: SoundStage! Solo, November 2022

I measured the Focal Bathys headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. A Reiyin WT-HD06 Bluetooth transmitter was used to send signals from the Clio 12 QC to the headphones, and for the USB input measurements, I connected the headphones directly to the computer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Bathys headphones’ frequency response with the wired connection in Silent mode. There’s an unusual bump in the response centered at 500Hz (which I didn’t notice in my listening tests), less energy at 2kHz than we usually see, and a lot of treble energy between 2.5 and 8.5kHz (which I did notice in my listening tests).

This chart shows the difference in response between the Bluetooth connection, the DAC (USB) connection, and the wired connection, all in Silent mode. There’s basically no difference. You can see a bit of a dip in the bass with the Bluetooth measurement, but that may be because I had to gate it more aggressively because of the added latency. Although it’s not shown here, the response was not affected when I switched noise-canceling modes, which is impressive—most headphones show some change in response in this case.

This chart shows the Bathys headphones’ response in wired mode with ANC on compared with the Mark Levinson N⁰ 5909 (which are said to be very close to an ideal Harman curve response), the DALI IO-6, and Apple AirPods Max headphones. There are a lot of very different-looking curves here, and the Bathys headphones sit somewhere in the middle. Probably not a bad thing.

The Bathys headphones’ right-channel spectral-decay plot (measured with the wired connection) looks clean, with no significant resonances.

Here’s the THD vs. frequency, measured using the wired connection in Silent mode at 90dBA and 100dBA (both levels set with pink noise). The distortion’s a little high in the midrange, but as it doesn’t rise with output level, this might be an artifact of the latency in the digital signal processing. The distortion in the bass is real, because it rises with output level. However, considering that 10% THD is a generally accepted threshold of audibility of bass distortion, I doubt it’d be noticeable.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. The Bathys headphones are competitive with some of the best noise-canceling headphones on the market. That’s impressive—I might expect a high-end brand that sells mostly on sound and reputation to just slap a noise-canceling chip in there and call it a day, but they really worked on the noise canceling here. (This is with all models set for maximum noise canceling, by the way.)

This chart shows how the different noise-canceling modes in the headphones compare, and what the passive isolation (with the headphones turned off) looks like. This is about what I’d expect from these modes.

Latency, measured with the Reiyin Bluetooth transmitter in aptX mode (my transmitter has aptX Low Latency, but not the aptX Adaptive codec included in the Bathys headphones), in DAC mode (USB connection), and wired mode, averaged about 285ms, 110ms, and 38ms, respectively.

The impedance magnitude, measured in wired mode with power on, measures 1530 ohms, and the phase is flat. This is typical of active headphones.

Bottom line: The Bathys headphones’ measured performance is generally excellent. The noise canceling is nearly world-class, and the frequency response looks pretty normal, although the measurement does seem to confirm my impression that these headphones sound a little bright.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 November 2022

Reviewed on: SoundStage! Solo, November 2022

I measured the QC Earbuds IIs using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. I used a Reiyin WT-HD06 Bluetooth transmitter to get signals into the earphones. I used the supplied medium silicone tips for all measurements because they fit best in the ear simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that I’m unable to do spectral-decay measurements on most true wireless earphones due to the latency. If you’d like to learn more about what our measurements mean, click here.

Unfortunately, something about these earphones and their ability to interface with my measurements gear gave me a great deal of trouble getting usable measurements with my usual techniques. I ended up getting latency that was too high for the Clio analyzer to deal with. So I had to do response measurements using pink noise with a real-time analyzer. This results in measurements that look different from what I usually present, and fewer measurements than I usually present. However, I did not notice any operational or latency problems when listening to the earphones.

This chart shows the frequency response of the QC Earbuds IIs versus the Google Pixel Buds Pro earphones and the TinHiFi T3 Plus earphones, a design I like a lot. Sorry, folks, best I can do—I didn’t have a lot of other samples on hand to run this measurement on, and my usual measurements use a different technique that’s not comparable. Anyway, the QC Earbuds IIs’ response looks pretty normal, and, in fact, rather Harman curve-ish.

Here we can see the differences among the QC Earbuds IIs’ noise canceling and transparency modes: ANC at max, Home, and Aware. It’s interesting to see how the Home mode works—it basically seems to turn the QC Earbuds IIs into something like an open-back headphone design.

Here’s how the Bose QC Earbuds IIs’ noise canceling compares to many competitors’ earphones. In most cases, the Earbuds II earphones beat them dramatically—even models that have pretty decent noise canceling. The only earphones that really compete are the Technics EAH-AZ70s, which more or less equal the QC Earbuds IIs’ performance in the bass, but can’t match the performance above 1kHz. Had I not used these earphones on some dog walks and a couple of airplane flights, I’d assume Bose got that result through better acoustical isolation, because all noise-canceling designs I’ve tried before limit the noise canceling to frequencies below about 800Hz, in order to prevent feedback. But I didn’t note an especially tight fit or ear-filling design with these, so I think Bose may have found some way to get noise canceling to work at higher frequencies, perhaps through active feedback cancellation. Regardless, I agree with Geoffrey Morrison that these earphones deliver a combination of noise canceling and isolation that’s dramatically better than I’ve experienced in any competing product.

Bottom line: Wish I could find a way to dig deeper into these technically, but what I see in these limited measurements is pretty impressive.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 October 2022

Reviewed on: SoundStage! Solo, October 2022

I measured the Beyerdynamic Xelento Remote earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The earphones were amplified using a Musical Fidelity V-CAN amplifier. Except as noted, I used the supplied medium-sized silicone tips for all measurements because they fit best in the ear simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Xelento Remotes’ frequency response. Hey, I said these were unusual! There’s a substantial bass bump below 200Hz; a very uncommon (but mild) boost in the midrange around 1.4kHz; some very narrow peaks centered at 5.2 and 7.2kHz; and an overall downward tilt to the tonal balance. From hearing them, I’d never have thought this is the way they’d measure.

This chart shows how the Xelento Remotes’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. There’s no difference that the human ear could pick up.

This chart shows the Xelento Remotes’ right-channel response compared with various earphones, including the AKG N5005s, which are said to be the passive earphones that come closest to the Harman curve. All the other models have a peak in the 2-to-4kHz range, like most headphones and earphones do. The Xelento Remotes do not. I’d finish this paragraph by holding down the question-mark key for several seconds, followed by a couple more seconds on the exclamation-point key, but the SoundStage! editors would just take them out.

The Xelento Remotes’ spectral-decay plot looks unusual, too. There’s some kind of apparent resonance in the bass, probably having to do with that big bump in the frequency response. There are also some super-high-Q resonances at about 2.5, 3.7, and 4.4kHz; they’re so narrow you’d never hear them, but they are yet another clue as to these earphones’ singular nature.

Very, very, very low distortion here—so yet again, unusual!

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. In the 43AG ear/cheek simulator, the Xelento Remote earphones, to my surprise, given their compact size, achieved extraordinary levels of isolation, especially when I used the foam tips. This would make them great for frequent flyers who don’t like noise canceling.

The impedance curve of the Xelento Remotes is pretty flat, averaging about 19 ohms, although both the magnitude and phase response rise at high frequencies.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 16 ohms rated impedance, is 112.1dB, which means the Xelento Remotes will play loudly from any source device.

Bottom line: There earphones seem very well made, with robust drivers, but the frequency response is quite unusual. If you read the review, you know I liked the sound, but this is one of those audio products that’s best tried before purchased—unless you’re a well-heeled audio enthusiast in search of something out of the ordinary.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 October 2022

Reviewed on: SoundStage! Solo, October 2022

I measured the Edifier NeoBuds S earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. I used a Reiyin WT-HD06 Bluetooth transmitter to get signals into the earphones. I used the supplied medium silicone tips for all measurements because they fit best in the ear simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that I’m unable to do spectral-decay measurements on most true wireless earphones due to the latency. If you’d like to learn more about what our measurements mean, click here.

This chart shows the NeoBuds’ frequency response with ANC on in the default EQ mode (Classic). This is a very standard, typical response, similar to the Harman curve.

This chart shows how the NeoBuds’ tonal balance changes when ANC is switched on and off. These will sound substantially softer with the ANC switched on—a situation that’s getting to be a bit old-school, because the DSP available in today’s true wireless earphones has allowed many manufacturers to get a near-perfect match in response whether ANC is on or off.

This chart shows the NeoBuds’ right-channel response (again, in ANC mode, and Classic EQ mode) compared with various earphones—including the KEF Mu3 earphones, which stick close to the Harman curve. In one way, the NeoBuds S earphones come closer to the Harman curve than the Mu3s do; they don’t have as much upper bass energy, which can make headphones and earphones sound muddy.

The NeoBuds’ distortion is shown here at the loud level of 90dBA (measured with pink noise), and the crazy-loud level of 97dBA. (I’d normally measure at 100dBA, but these earphones won’t play that loud.) At 97dBA, there’s a distortion peak of 3.7% THD at around 4.5kHz, a range in which the ear is pretty sensitive, but it’s a high-Q (i.e., narrow) peak, so it probably won’t be noticeable, or aggravated all that much unless you’re playing music with a lot of high-frequency content.

Here we can see the differences among the NeoBuds’ noise-canceling modes: ANC on and off, and Ambient. The red line represents the 85dB SPL baseline for the measurement; the lower the curve goes below that line, the better the isolation. This is about how these modes should be expected to perform.

Here’s a comparison of the noise-canceling capabilities of the NeoBuds, the new Bose QC Earbuds IIs (soon to be reviewed), the new Apple AirPods Pro 2s, and the LG Tone Free T90Qs. The Edifiers can’t beat the Bose earphones (I doubt any earphones currently on the market can), but they deliver a respectable and useful amount of noise canceling nonetheless.

Latency with the NeoBuds was typically about 310ms with the Reiyin transmitter, which is typical for true wireless earphones. Unfortunately, I don’t know of a way to test the earphones’ low-latency gaming mode.

Bottom line: Solid performance here all-around.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 October 2022

Reviewed on: SoundStage! Solo, October 2022

I measured the Meze Audio 109 Pro headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the 109 Pros’ frequency response. There’s nothing particularly noteworthy here, it looks pretty typical for an open-back model—more or less flat below 1kHz, with a typical peak in the 3kHz range.

Here we can see the difference in the headphones’ response when a high-impedance (75 ohms) source is substituted for a typical low-impedance source (5 ohms). With the high-impedance source, the bass is boosted by about 1dB between 40 and 150Hz, which will be an audible but subtle difference.

This chart shows the 109 Pros’ right-channel response compared with a few other open-back models (including the Dan Clark Audio Æon 2s with perfed pads, which are the open-back headphones I’ve found come closest to the Harman curve). The 109 Pros seem well within the ballpark of normal.

Just for fun, I did a comparison of all the high-end Meze models in one chart. Interestingly, the 109 Pros seem to have bass that’s similar to the Empyreans, with treble that’s similar to the Elites.

The 190 Pros’ spectral decay is surprisingly clean for an open-back model; there’s a little bit of the super-high-Q midrange hash I’m used to seeing with these types of headphones, but much less than usual, which suggests that either the driver is well-damped or there’s some sort of acoustical damping going on, perhaps surrounding the driver on the ear side of the baffle.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA, both levels set with pink noise. (Apologies for using 50% as the max value on the distortion scale; I usually use 20%.) Distortion in the bass is a little high, at roughly 5% at 20Hz; strangely, the distortion increased only marginally with the higher-level signal. Anyway, bass distortion is much less audible than midrange distortion, because the distortion harmonics fall mostly outside the ear’s most sensitive range, so I don’t expect this to be much of a problem.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. The 109 Pros’ isolation is surprisingly low for a design based on a 50mm driver; this means these headphones may have a somewhat more open sound than most dynamic-driver open-back models, although they won’t block a significant amount of external sound.

The impedance of the 109 Pros mostly averages around 43 ohms, with a mild bump and corresponding phase shift in the bass that’s pretty common for dynamic drivers. This suggests there’ll be a very slight, and possibly inaudible, difference in bass response when you go from a low-impedance source to a high-impedance one.

Sensitivity of the 109 Pros, calculated for 40 ohms impedance and averaged from 300Hz to 3kHz, is 110.4dB; I can’t imagine there’s a source device that couldn’t get these cranking loud.

Bottom line: The Pros include safe’n’sane frequency response, very low resonance, and awesomely high sensitivity. The only con I can see is that the distortion’s a little high, but as I stated, given the frequency band where the distortion occurs, I doubt you’ll notice it. I didn’t.

. . . Brent Butterworth
brentb@soundstagenetwork.com