You're right...the Valhalla 2 is not by any means your traditional warm tube amp. Within the world of tube amps, it leans towards a more lean and clinical presentation. In my opinion, the HD600 and HD650 both benefit from this. The 650 especially. Though, again, I'm not tossing the Ember under the bus here. It does just fine with the HD lineup.
7/8/16 at 10:23pm