Sound So, this is my first legitimate tube amp and color me impressed. I have been using it with a pair of Sennheiser HD595 headphones, a pair of Stax Lambda Pro earspeakers, and a pair of Polk Audio R300 speakers. So far, it has driven them all well. I would suggest replacing the stock tubes with something a bit better though. So far, I have been using NOS GE tubes and they work great (they are a bit smaller in height than the stock tubes, but don't be alarmed, they fit and function perfectly.) The sound signature is a little dark. It has a...