[Tyson]

Big power supply, large power output.  Can be tube or solid state.  I use a custom build headphone amp using a 6sn7 driver tube and 6bl7 output tubes.  Sounds very good. 

[JohnR]

To wrap this one up - I sold the T1s. I had a few great moments with them, but in the end they weren't my cup of tea. FWIW I've realized that tea is a hard brew to make, when each person has a different idea of what tea "should" be like.