I just bought a used Rogue audio st100 tube amp and was wondering what everyone thoughts are as far as tube upgrades.I use a rp1 preamp and Nht 2.9 speakers
Amp has
Two PS Vane 12AU7
Tubes, Two PS Vane 12AX7 Tubes, Four Tung-Sol KT120
I also run a pair of gold lion 12au7 /ecc82 in the rp1
If the current tubes are OK, I doubt changing them will make a difference. Mullard are good reliable tubes.
It is an absolute myth that tube gear sounds better then solid state gear, in fact it is worse, and drifts out of spec, as the tubes age. In addition the output impedance is high because of the output transformer. This makes the output want to follow the impedance curve of the speakers.
You pay a lot of money for not a lot of power. Power is important because of the huge dynamic range of music, which is now realized by the huge dynamic range made possible by digital media.
There is absolutely no reason to be using tube amps in this day and age. That is just audiophool fantasy. They are inferior to good modern solid state designs, and actually many older solid state designs.