Pros: Best sound I have yet heard
Cons: Can be some tube hum if not chosen well
I haven't had it for too terribly long, nor have I had the fortune of being able to sample many different amps. This amp has surpassed my expectations. I came to this amp from a Compass DAC+Amp which still acts as my DAC. The difference was night and day.
I'll keep it simple; I find myself wanting to listen to music MORE after receiving this amp.
Using HD650 and DT770s for now.
Using RCA 6AS7G black plates and Tung Sol 6SJ7GT mesh plates. The RCAs are slightly tubey while the TSs are more neutral, a winning combination.
I purchased this amp so I could also gauge my own open source DIY amp that I am designing to "give back" to the community in my own way. I figured what better amp to judge my own successes and failures by then a staple of the audiophile world.
My version of the 337 is the 2009 version. It looks different from the model represented in the pictures here. It is more mat black and industrial looking instead of classical piano gloss black looking. I honestly favor the more modern industrial look.