i'm just listening my AKG K601 on the project starlight with standards OPA (LM4562na) and a 12V RCA cleartop (Wurlitzer version "cheap but good"), source is a cheap HifiMeDiy Sabre USB DAC (42$) this config sounds great, great details with such a tiny DAC, background is silent, clean sound, great dynamics, and highs aren't sounding artificially harsh (although the HifiMeDiy DAC is slightly sibilant for my taste), and soundstage include both deep and width (like more expensive SS desktop amp i've tried like Audio-GD C2), and above all, listening music through this little amp is a pleasure.
The most surprising thing is that little amp is very powerful, on the AKG K601with output impedance set on 68 Ohm (the less powerful settings) i can't exceed 30% of the volume pot without risk to hurt my ears, I was expecting a lot less power than the first "Project Sunrise", this is not the case, and this is the most surprising for such a configuration (valve & 4 x OPA Class [size=medium]
AB[/size]).
No problem to drive the 160 Ohms K601, i will try later with a most detailed DAC with more "chest" (Audio-GD DAC 19-DSP), the Project Sunrise deserves better than the cheap (but good) Hifimediy DAC.
I Will try later with 4 x OPA2604 and an ECC86 (my favorite valve on low voltage preamplifier), will keep you informed.
But for now I'm busy, listening music is very time consuming