Power amp + CDP: is that enough?

Rrog has summed it up nicely. I've had a Sony XA7ES player and tried driving the power amp directly, bypassing the preamp. Although the sound is cleaner which gives an impression or illusion of a purer sound with higher levels of refinement, there is just something missing in the music. The dynamic shadings are somewhat missing, the punch and drive in music. In other words, music sounds a bit flat.

I've managed to listen to a high-end DAC driving a Krell FPB amp directly at a friend's place, a dCS Debussy. We A/B'd between running the DAC directly and having the preamp in the chain. Although the DAC gave very good results driving the amp directly, producing a transparent and almost faultless sound, the same phenomena still applies. Having said that, I can probably live without the preamp with the dCS Debussy. The preamp brings a tiny bit of involvement into the music, small but appreciable.

In summary, with the Sony CDP, for the best results I feel it's best not to drive the power amp directly with the internal volume control of the player, though there is no harm if you want to try and see how things work out for yourself.

Cheers.

There are a number of unpredictable and unspecified variables that are involved, that are component-dependent. I would be cautious in extrapolating from reported experiences that are not based on the same CDP.

Some relevant factors that haven't been mentioned are the output impedance of the player, how that output impedance varies as a function of frequency, the length of the interconnect cable, various technical characteristics of the interconnect cable, and the input impedance of the power amp.

The output impedance of the CDP does not appear to be specified, but its recommended minimum load impedance is 10K. While most power amps will conform to that requirement, the fact that that recommendation is made suggests that the output impedance of the CDP is not particularly low, which is not encouraging.

The full scale (maximum) output voltage specification is 2 volts, as is often the case with CDP's. That suggests that the power amplifier should have a sensitivity rating (the input voltage required to drive it to full power) of not much more than 1 volt, and preferably less. Otherwise you may not be able to turn the volume control up far enough to utilize all of the amplifier's power capability, should that be necessary with some material having wide dynamic range.

Regards,
-- Al

A lot depends on how the CDP implements the volume control.

I have found that if the gain on the power amp is high, a digital volume control is usually less effective. If the power amp has a low enough gain and you can dial up the digital volume control high enough, it may be a better match.

The other issue I find, even when the gains match is that while a direct connection provides a "purer" more direct signal, the soundstage feels a bit flat and more 2D.

Providing a good preamp in the chain expands the soundstage, particularly in terms of depth.

And then you have something ilke the Ayon CD5S which adds a true analog preamp stage. That IMHO is something that has to be heard to be believed. I use it directly to the power amp in a second system. It's that good.