...of my Matchless Thunderchief. I don't know a whole lot about this, so a tech will be performing all the work. However, I will buy the tubes before they are installed, so I'd like some TB opinon. The TC is a 200 watt all tube Class A head, and I believe it originally came with KT100s. When I bought it, it had 4 KT88s, 2 of them blown (By the way, if I've used it with the blown tubes, have I damaged the amp?...haven't used it with any high volume at all). Should I go with KT88s? Can I use EL34s? 6CA7s? I've done the search and reading so I know the basic differences, but don't know which tube type would be best for this head. I definitely don't want to tax the amp and risk killing it. Thanks to all for their help, I desperately need it!