The sylvania 6ca7's are a bit rare these days (thanx mr. evh!) I have found the Ruby STR-el34B un8its to be VERY similar to the Sylvania 6ca7's, and even hold up decently well in a music man which is konwn for putting over 700v on the plates... sound wise very similar... at 'clean' volumes, they are a bit more 'musical' than an el34 (which caqn tend to sound almost sterile in some guitar amps)... i mena the 6ca7 wont sound just like a 6l6, but in the music mans, can make them sound welll fendery *laugh*. Cranked, they compress a bit like an el34, but hold some top like a 6l6. EVH was known to use the sylvania 6ca7's in his plexi, partially responsible for his so-coveted tone. The Ruby's are a great value, and probably the only chinese power tube I would consider. I got t5he set that I tried from Lord Valve at NBS electronics (sorry, dont know the webpage off the top of my head!). I paid $50 for a matched quad, so the price is right as well. (Just make sure you get the str-el34B, the el34a just are NOT hte same *laugh*)
"I would love to find some 6CA7's. Where should I look and how much should I expect to pay?"