Do Audiophiles usually keep the gain of the digital source at around 80%?

I meant Innuos.

Have you tried bypassing the McIntosh and use the a8 As the preamp. 

+1 for 100%

Only digital components meant to drive a power amp directly (no preamp needed) have a volume control.

In most cases that digital volume control is cheap trash. The more you turn it down the worse it sounds, hence the advice to keep it at full volume all the time so it’s essentially not being used (remember these are attenuators, so the more they attenuate the sound the more impact on sound quality they have).

The downside of keeping the VC at 100% when you do use a pre is that these components have a LOT of gain because, well, they’re designed to work without a pre! So, as you’ve observed, you need to turn your pre’s volume way down compared to other sources.

If you’re going to use a good pre, which is highly recommended, then you’re going to control volume at the pre, so that upstream VCs are not needed; so, digital components that have one should be avoided.

@lanx0003 

I believe the A8 supports ReplayGain, allowing you to apply it to individual tracks or entire albums. ReplayGain doesn’t involve any re-encoding or lossy digital processing—it’s simply like having a servant or robot adjust the playback volume for you.

If the gain is applied in the digital domain, the digital calculations will be ’lossy’ because not all fractional numbers can be represented digitally by a finite number of bits.  To give a decimal example, the fraction one-third requires an infinite number of decimal places to be represented exactly.  If only a fixed number of places is available, there will be rounding errors.  It is far worse if the calculations have to be done with whole numbers, as is common in digital audio!

Now if your servant or robot is twiddling an analogue volume knob via a motor, this consideration does not apply.  I find this scenario unlikely, although I have enjoyed Denon components with a remotely controlled volume knob.

For what it is worth, the term gain only makes sense once the signal is analogue.  By convention, digital conversion to analogue includes amplification to produce consumer line-level analogue outputs - about 1-Volt.

Sneaky manufacturers like to lift this output level because when doing A / B comparisons, louder almost always sounds better.  The corollary is that this can overload a pre-amplifier's input!

Digital gain at 100% and preamp gain 30-50% is generally the ideal operating range but at 60-70 DB there should be no audible distortion in a properly configured system.