Audiolab 9000P Stereo/Mono Amplifier

Link: reviewed by Roger Kanno on SoundStage! Hi-Fi on June 1, 2026

General information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The Audiolab 9000P was conditioned for 1 hour at 1/8th full rated power (~12W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The 9000P is primarily two-channel amplifier with switchable balanced (XLR) and unbalanced (RCA) inputs, and one set of speaker-level outputs. An input of 635mVrms (XLR) was required to achieve the reference 10W into 8 ohms. The 9000P can also be bridged to mono operation.

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency, where a bandwidth of 10Hz-90kHz was used. Frequency response measurements utilize a DC to 1 MHz input bandwidth.

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Audiolab for the 9000P compared directly against our own. The published specifications are sourced from Audiolab’s website, either directly or from the manual available for download, or a combination thereof. Assume, unless otherwise stated, 10W into 8 ohms and a measurement input bandwidth of 10Hz to 22.4kHz:

Our primary measurements revealed the following (unless specified, assume a 1kHz sinewave at 635mVrms at the input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

*protection circuit triggered beyond this point

For the continuous dynamic power test, the 9000P was able to sustain about 183W into 4 ohms (~4% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (18.3W) for 5s, for five continuous minutes without inducing a fault or the initiation of a protective circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the top of the 9000P was warm to the touch.

Frequency response (8-ohm loading)

In our frequency-response (relative to 1kHz) plot above, measured across the speaker outputs at 10W into 8 ohms, the 9000P exhibits a near-flat frequency response across the audioband (0/-0.1dB at 20Hz/20kHz). The 9000P is nearly flat down to 5Hz (-0.1dB). The -3dB point is beyond 200kHz.

Phase response (8-ohm loading)

Above is the phase response plot from 20Hz to 20kHz for the balanced line-level input, measured across the speaker outputs at 10W into 8 ohms. The 9000P does not invert polarity and exhibits, at worst, only -10 degrees of phase shift at 20kHz, due to its extended bandwidth.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 10Hz to 100kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we find the maximum deviation between an 8-ohm load and no-load to be around 0.06dB up to 4-5kHz. Beyond 5kHz, the deviations are as high as 0.14dB at 20kHz. This is an indication of a high damping factor, or low output impedance. With a real speaker, the deviations from 20Hz to 2kHz were roughly the same (0.06dB) from 20Hz to 10kHz.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the output into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue plot is at 1W output into 8 ohms, purple at 10W, and pink is at the rated power (100W). The 1W and 10W data are close (within 2-3dB) and range from 0.0006-0.0008% from 20Hz to 1kHz, then up to 0.01% at 20kHz. The 100W THD data are higher, ranging from 0.2% at 20Hz, down to 0.04-0.08% from 50Hz to 6kHz. Above 10kHz, the protection circuit engaged, which explains the spike in THD.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms (8-ohm taps)

The chart above shows THD ratios measured at the output of the 9000P as a function of output power for the analog line-level input, for an 8-ohm load (blue/red) and a 4-ohm load (purple/green). The 8-ohm data ranged from 0.002% at 50mW, down to 0.0006% from 20W to the “knee” at 90W. The 4-ohm data ranged from 0.003% at 50mW, down to 0.001% from 30W to the “knee” at roughly 150W. The 1% THD marks were reached at 104W and 168W into 8 and 4 ohms.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms (8-ohm taps)

The chart above shows THD+N ratios measured at the output of the 9000P as a function of output power for the analog line-level-input, for an 8-ohm load (blue/red) and a 4-ohm load (purple/green). The 8-ohm data ranged from 0.015% at 50mW, down to 0.0007% from 50W to the “knee.” The 4-ohm data ranged from 0.02% at 50mW, down to 0.0015% from 50W to the “knee.”

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the 9000P as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields roughly 25W at the output into 8 ohms (blue), 50W into 4 ohms (purple), and 100W into 2 ohms (pink). The 8-ohm data ranged from 0.0005% from 20Hz to 600Hz, then up to 0.015% at 20kHz. The 4-ohm THD data followed the same trend but with about 5dB more THD. The 2-ohm THD data followed the same trend but with about 6-7dB more THD than the 4-ohm data.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the 9000P as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). At very low frequencies, the two-way speaker yielded the highest THD ratios at 0.05%, then the three-way speaker at 0.003%, compared to the resistive load at 0.0008%. At 100Hz, the real speakers yielded about 0.003% THD compared to the resistive load at 0.0008%. In the midrange frequencies (500Hz to 5kHz), THD ratios were closer (all three traces within about 5dB) in the 0.0005% to 0.003% range. At 20-kHz, the three-way speaker yielded the highest result at 0.025%, compared to the two-way speaker and resistive load at around 0.01%.

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the 9000P as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). The IMD results into the resistive load range are fairly consistent, from 0.0005 to 0.0008% across the sweep. The results were higher into real speakers, ranging from 0.001% to 0.008%.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the 9000P as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input in stereo mode. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz, and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). All three plots are very close and constant at 0.004-0.005%.

FFT spectrum – 1kHz (XLR line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. We see that the signal’s second (2kHz) and third (3kHz) harmonics dominate at roughly -110dBrA, or 0.0003%. Other signal harmonics can be seen at just above and below the -120dBrA, or 0.0001%, level. There are power-supply noise related harmonics at the -110dBrA to -130dBrA level, or 0.0003% to 0.00003%.

FFT spectrum – 1kHz (RCA line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the unbalanced analog line-level input. We see effectively the same FFT as with the balanced input above.

FFT spectrum – 1kHz (XLR line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the balanced analog line-level input in bridged mode. Generally, both the signal harmonics and power-supply noise harmonics are higher in bridged mode. The second (2kHz) signal harmonic reaches -100dBrA, or 0.001%, and the primary (60Hz) and fifth (300Hz) power-supply noise harmonics reach -105dBrA, or 0.0006%.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the balanced analog line-level input in stereo mode. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most dominant (non-signal) peak is the signal’s third (150Hz) harmonic at -105dBrA, or 0.0006%. There are power-supply noise-related harmonics reaching -110dBrA, or 0.0003%, at 60Hz and 120Hz.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The input RMS values were set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at the very low -120dBrA, or 0.0001%, level, while the third-order modulation products, at 17kHz and 20kHz, are higher at the -100dBrA, or 0.001%.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the 9000P with the APx 32-tone signal applied to the input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are below the low -120dBrA, or 0.0001%, level.

Square-wave response (10kHz)

Above is the 10kHz squarewave response using the balanced analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the 9000P’s slew-rate performance. Rather, it should be seen as a qualitative representation of the 9000P’s wide bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we see a very clean result, with no ringing in the corners and only very mild softening.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We find high damping factor values, from 230-250 from 20Hz to 2kHz. Above 2kHz, there is a dip in damping factor, reaching about 120 at 20kHz. This is a strong damping factor result.

Diego Estan
Electronics Measurement Specialist