I've only had experience with Chinese tubes in my Sovtek Mig50. They seemed to sound really fizzy on the top end compared to the tubes that were in it before. I wish i could remember what tubes were in before. What tubes would you guys suggest for a '67 Bassman head? I want a thick dimensional tone that just fills. Good breakup, but I don't want to loose bass response. I'm not sure how much preamp tubes can effect this, but I'd love some suggestions!