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!