don't think it was the tubes, more likely the dampers just weren't the right thing for my dac
More likely the tubes. I have herbies dampers on all my tubes, but have experimented with and without them and, frankly, have noticed no discernable difference unless a tube is truly microphonic (e.g. it rings or pops when I tap on it while playing music), in which case a damper seems to help. Personnally, I have never experienced a situation where a damper actually "damped" the tone or performance of an otherwise good tube. On the other hand, individual and pairs/sets of tubes certainly can vary tremendously in performance, so the replacement of the tubes seems the most likely explanation for the improvement. IMHO. In any event, glad you were able to resolve the problem. AN DAC's are very good and are certainly sexier in a high end system than Oppo or DAC Magic :)