Using CD player without Preamp?

I agree with Polk as long as the output stage was actually designed to drive a power amp. Despite having a nominal output high enough many CD players will not be as good as a good preamp in driving a power amp. But if they have been designed to do so then adding anything else will degrade the sound to some degree.

Stan -- You made a similar statement in the other recent thread that you referenced, which was questioned by another member. Please explain how the output stage of a cd player would "know" whether it is driving a preamp or a power amp, assuming the input impedances of the preamp and power amp are comparable, and the cable length that would be run to either device is the same. Also, how is one supposed to know if the output stage of the cd player is "designed to drive a power amp"?

I can certainly envision reasons why a specific combination of cd player and power amp might sound either better or worse with or without a preamp in between, some of which were mentioned in the other thread:

http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1228927169

But pending your answer I would not speak of a cd player as being "designed to drive a power amp."

Regards,
-- Al

Kr4...There you said it!! "If the VC is digital (and, therefore, loses data when attenuated)...". Maybe you could explain how data is lost. It doesn't have to be so.

If the data was left shifted the LSB would indeed be lost, but the remaining bits would be worth half their original voltage, and no digital volume control I have heard has steps that large.

Al, there are specific DACs which are intended to be used without an active preamp. My Audio Synthesis Dax is one. It has a much higher quality output section than a cheap integrated player. The question does not involve the device in question KNOWING what it is driving but the quality of the output stage in it. A cheap stage will do better supplying a small signal to a good preamp than doing the whole job itself. Such DACs will naturally be more expensive and complex as they are doing a job the others were not really designed for. Check the Audio Synthesis web site for their take on this.

Maybe you could explain how data is lost. It doesn't have to be so.

It is lost through "quantization" error due to rounding. Normally a CD will be dithered when it is produced from a higher resolution source - preserving 93 db SPL of dynamic range. Not ALL digital volume controls are implemented properly and include the necssary dithering. I think that was what Kal's warning is about.

If you turn the volume down to low levels you may be left with only 5 bits with loads of horrible harmonic distortion - if this is simply truncated or re-sampled rather than re-dithered before re-sampling then it can sound awful....many PC software volume controls do this and sound awful - PC audioo can be a minefield.