Don't disagree on the thought of speaker upgrade. Here is the rationale:
- 12L2s sounds great out of the NAD and I was recently able to hear them driven by Bel canto 500 - sounded incredible (REL sub helps really bring out bass on orchestral music).
- I can do the benchmark, bel canto CD2 and nuforce/wyred/bel canto amp at around $6-$7k all in (a'gon purchases);
- The speaker upgrade is next - have listened to Dynaudio Confidence C2 with good class D and really incredible - $12k - next year.
FWIW - class D seems to have gotten good enough that the green side of me would not consider large wattage, large footprint class a/b.