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On the Bench As I said previously, I was not able to get measurements on the GCA MC-500 because of switching noise interfering with my test software (a problem with my software, not the amplifier, as all switching products produce this noise), so here are the graphs on just the GCP 200 preamplifier. All graphs were taken from the XLR output. At 1 kHz and 1 volt RMS output, THD+N was less than 0.02%. Maximum voltage output before clipping was 8.68 volts RMS via XLR and half that through the unbalanced RCA output. This is right on spec. The signal to noise ratio at 1 kHz and 1 volt output was 115 dB. This is excellent, and it means you won't be hearing any hiss or hum from the preamplifier during quiet music passages.
For 1 kHz and 1.5 kHz test signals, the A+B IMD peak at 2.5 kHz was 79 dB below the fundamental, while the B-A peak at 500 Hz was 76 dB below the fundamental.
Using 5 kHz and 6 kHz for the input, the A+B IMD peak at 11 kHz was 79 dB below the fundamental, and the B-A peak at 1 kHz was also 79 dB below.
THD+N was still less than 0.02% with a 10 kHz input sine wave and 1 volt RMS output.
For 10 kHz and 11 kHz sine wave inputs, the A+B IMD peak at 21 kHz was 77 dB below the fundamental, and the B-A peak at 1 kHz was 78 dB below.
The measured frequency response was 10 Hz - 90 kHz ± 0.1 dB. This is a very flat response.
Conclusions PS Audio's GCP-200 Preamplifier and GCA MC-500 Power Amplifier are not only great products, they are a lot of fun! The two-channel preamp is novel in that it lets you name the inputs and set the input gain, which is more like a modern SSP than a stereo preamplifier. Although digital switching power amplifiers that cover the full audible range and do it well have been long in development, the wait is over. The GCA MC-500 is one of the most powerful multi-channel amplifiers in the world, and if you like action movies as I do, power is good. Transients are reproduced faithfully, which is very important in realistic sound, whether it be Rachmaninov Preludes, or an AK-47. All the while, the power amp runs cool and uses less electricity. Quality never comes cheap, and the PS Audios are no exception, but for those of us patient enough to put some bucks away in a savings account for a system like this, PS Audio will be there.
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