The BHK 300 is a hybrid amplifier made by PS Audio. It uses a tube input stage of two 6922 tubes, and a solid-state output stage. This gives it some "tubey" sound qualities with the power and control of a solid-state amp. You can even roll tubes in it to tune the sound somewhat. I like it very much, but it is a different beast than an SET amp. I have no idea how the Ulf's would sound on a small tube amp, but some of my recordings definitely benefit from the extra power that the BHK's provide.