chihwahli
Head-Fier
Many people don't like tube amp's either.
Because Tubes color the sound and are not a reference/analytical sound.
If you want something that is analytical either look at o2Amp or maybe an Asguard 2..
There are lots of cheap offerings too which can power heavy phones, like the SMSL VA2 and FiiO E9, etc.
The Asguard 2 is considered warmer than version one. Not sure how much warmer a Valhalla 2 is compared to the Asguard 2. This makes the choice a bit more difficult. But Since the DT880 600 is quiet neutral, a bit of coloring would not hurt. I am not the 100% analytical listener. =)
http://www.ayonaudio.com/ayon/why-tube-amplifiers.html
Hmm,, Tube still.