1st, go to the tube asylum... http://www.audioasylum.com/scripts/tv.pl?forum=tubes&s=U ...and SEARCH there; you'll find a lot. If you decide on '88s, I recommend the Penta/Shuguang KT88SC. They're only $29 each and sound quite nice. I changed from the original Shuguangs in my ASL 'Canes so didn't notice a difference in sound, but these's a lot of info about them on the Asylum.
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