Hard to understand why they are still shipping units w/noisy tubes. When I took delivery of my Calypso about 2.5 years ago, it had one noisy stock tube (Teslov 12ax7). The dealer sent me a new pair at no charge; one of them were noisy. But between the two pairs, I was able to make a good quiet pair. But they weren't in very long (a few hours), as I replaced them with different 12ax7's. Long story short, I've been through a few different pairs of 12ax7's, the latest being Mullards, along with Amperex 6922's. Well, one of the Mullards was getting very noisy, and it was again time to revisit 12ax7's. Then, my unit broke. A diode went out in the power supply. When I shipped it back to Aesthetix, I put all the original tubes in it, including the two noisy Teslov 12ax7's. I asked them to retube my unit with quiet tubes, which they did, at no charge. I thought I would give the stock tubes a chance, and after a couple of hundred hours, I'm pretty pleased with how they are sounding and I think I'm gonna leave as is. I may however pop the Amperex 6922's back in at some point, but again, it's sounding pretty darn good. At max volume listening level (jumpers set to -12db cut), one has to put your ear right next to the tweeter to hear anything. Dare I say, solid state quiet...