The Isone Pro is absolutely trash in contrast to the Realiser which I demoed back in CanJam 2009. I couldn't distinguish between whether I was listening to their speakers or the headphone. Yea, it's THAT convincing.
Standing waves, exist in rooms of ANY dimension, simple as that. As I said earlier, carpet mostly absorbs high frequencies and does almost nothing for other frequencies which is what you should be worried about as high freqeuncies are the least of your problem. As for book cases, all I can say is that measure what you did and you'll see how well (or not) these book cases act as a bass trap or diffusor in terms of frequency response and on a waterfall graph. The...
I believe I had the Paradisea 3(don't recall the NOS tube I used), RSA HR2/Singlepower Extreme/Audio-Gd Phoenix, and a W5000/balanced HD650 at the time.
As I remember, the Electrocompaniet ECD1, which replaced my Paradisea, was a much more competent DAC.