Digital gain vs analog gain

Just because you don't understand something doesn't make it automatically "utter nonsense".

@ -6db you have given away 50% of the SNR. Digital or otherwise.

Every analog stage has overload conditions. So it really helps to understand the rough signal level (e.g. RMS Voltage) expected at each link in your chain, and to ensure you leave ample overload margin for the downstream component to handle that signal level (overload margins are often spec’d relative to a given RMS Voltage input level).

Digital sources these days often have very hot output (sometimes well in excess of 4 Volts on XLR outputs), and I wouldn’t worry about the using a well-implemented digital volume control (lots of bit depth, 64 or more bits and dithering) to keep the output levels reasonable, or just to do some L/R channel rebalancing for your system - as long as you’re not using it to attenuate TOO much.

Depending on the gain structure of your system, if you have too much gain and very sensitive speakers, sometimes it can help to have additional analog attenuation further downstream in order to push down the noise floor relative to signal.

Already useful. Had a little time today for some ear tweaking. iTunes slider at 0dB, preamp analog pot at 12 o’clock, Crown attenuators at 8 o’clock. As compared to my previous setting, Wharfedales were more forward, tweeter a bit brighter, bass tight and rich. Unscientific impressions were that the signal was more complete without noticeable distortion. Less relaxing but more engaging LOL

My initial question is well solved thanks to this discussion. The practical info about gain helped. With the analog preamp pot at 50%, iTunes slider at 0 db, and amp at 25% attenuation everything was more forward at a final volume comparable to before my question. Before, with the slider low and preamp pot way down so the amp could run at 100% it seems I had it all backwards…starving things out and pinching the signal to noise ratio.
 

Biggest proof? The amazing difference from my Wharfedale Lintons that I can induce at this new setting just by sliding the iTunes level between 85% and 100%. Volume changed just a little, but mid and treble imaging exploded in a good way every time I took it back to 100%!

I am not suprised at your findings. I have always been advised that one should set iTunes at full volume. Then set amp such that your preamp can be run between 10-2 o'clock depending on desired volume ( therefor around 12) . This is usually the sweet spot on most variable pots used in a preamp. 

One problem you have is the total gain you have between preamp and amplifier causing you to attenuate much of the available gain in the amplifier. Your compromise seems the best fit.