While Ciska here 100% agreed with me (subject to not being able to have a conversation and all), she came up with the idea that possibly it now becomes apparent that the lost bits because of too much digital attenuation (which to some extend *is* true) imply the better THD.
My 2 cents: Getting rid of my active pre (tube) was the right thing to do. It lowered the noise floor a lot and increased the level of detail but it also sounded flatter. I thought the flatter sound was because of removing the tubes from the signal chain but I was wrong on that.
After removing my pre I bought new and much better speakers and then a very good amplifier. Both I would call, within some limitations "state of the art". Still, I was not really happy with the sound. On some day I was and on some day I was not.
Also my system sounded worse in aspects of naturalness and 3D soundstaging than less expensive and less elaborated systems. I had no peace on my mind because of that and thought: WHY? WHY is my system not totally better than these systems? I also tried some components from theses systems in direct comparison to mine. None of the components was better. There was no reasonable explaination for me, except the one thing I could point out: These system use an analoge volume control. Finally I did some experiments with analog volume control vs. digital volume control.
For example I tried a DAC with an implemeted, selected alps poti. If I turned up the poti fully and used 40db of digital attenuation. The sound got flatter and less natural. AHA!
I tried the same with another DAC and a TVC (Transformer Volume Control). Same result!
Every time I tried and made a comparison the result was the same. Even some high quality pre amps can show some advantages in 3D soundstaging and naturalness over a properly implemented digital volume control. A good thing to do, seems to have an analoge volume control directly build in the DAC and have it "buffered" to avoid high frequency cut offs.
After using a good implemented analog volume control, I do not "suffer" from day to day sound differences any more. Maybe they are there but the sound gets not so much affected by these "daily variations". It sounds good every day. But the sound is defnitly not filtered to death. I can hear better than ever differences made in the digital domain.
Greetings
Adrian