Just dropping a recommendation for the new-production 6189 in the driver position of the Speedballed Crack. After about 50 hours, this tube is very clear and has a huge soundstage, but is very smooth and un-fatiguing at the same time. My HD650's now have a huge soundstage that beats my previous favorite tube, the 6CG7. Best of all, I paid about $10 for the tube, which I think is made by the same people who do the Electro-Harmonix brand (e.g., New Sensor). No complaints so far....
EDIT: Forgot to mention the brand name; they are using the old "Tung-Sol" moniker and box design for these.
EDIT: Forgot to mention the brand name; they are using the old "Tung-Sol" moniker and box design for these.