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Noise at high end of volume output on Cyrus Pre aCA7.5 preamp

rah

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Nov 23, 2019
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Hi all,

I recently bought a Cyrus Pre aCA7.5 preamp on eBay. I have a DAC going into an integrated amp. In preparation for an impending switch from the integrated amp to a new power amp, I've taken to putting the integrated amp's volume to maximum and using the volume control on the DAC.

I plugged the Pre aCA7.5 preamp in between the DAC and the integrated amp and put the preamp volume to maximum, as with the integrated amp. I was shocked to find the sudden introduction of vast amounts of audible noise when I had expected the same silence as with the DAC and integrated amp alone. This noise reduced if I turned down the volume control on the preamp.

The preamp had to go back because the volume knob had a problem but one would not expect that to effect the audio path because the knob was not a pot but a digital rotary input to a presumably computer-controlled volume control.

This has left me in something of a quandary. I prefer to control the volume of my system on the source, my computer. I rarely touch the volume control on the DAC now that I use its preamp mode, and similarly rarely touched the volume on the integrated amp before. If it's common for preamps to introduce noise with their volume control set to maximum then I would need to adapt, possibly by finding a preamp that can be controlled from the computer through RS232 or something similar.

So I have a question: should I expect a preamp set to its maximum volume to introduce lots of noise? I don't see the same kind of noise on my integrated amp (a NAD C370) when that's set to maximum so I don't see why this Cyrus preamp was so noisey. Is it perhaps just this preamp model? I'd like to stick with Cyrus because of the small size of their cases but this experience with the Pre aCA7.5 has made me wary. Should I expect other Cyrus preamps to be similarly noisey?

Thanks for any input.
 
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