So, I have an Orange TT combo, had it for a few years now. As most peopledo, i thought it might be time for a change of preamp tubes, maybe i could get better sound etc from the stockones. So i bought some JJs then some Tung-Sols. Oh dear. The JJs made the amp more muffled sounding, i could see how they would work in a brighter amp, smooths things too. The Tung Sols, wow, how flat and harsh are they! any elastic tube sound went south, it sounded like a solid state. So, back in went the stock ones, much better. Orange did a good job matching the tunes to the TT, so beware, not all changes to stock tubes are better (unless you want to spenta lot on NOS etc i guess).