hey,
from what I have heard, that's right, Siemens... they are supposed to be great. I had a quad in my Diezel Einstein and it sounded great. I put a pair in the simul sockets of my C+ and I wasn't too happy. Seemed a bit to fizzy. not tight enough, but maybe i didn't give them a fair chance because I had mesa STR 416 (6CA7's) to swap them with.
scott