SED(Wing C)6550's. Rugged, dependable, excellent quality. I've had one bummer in the past 10 years and it was too hot to bias in properly so it never got used. I bought it about 7 years ago but didn't use if 'til about 3 years ago. No other problems before or after. No shorts or premature deaths. Excellent bass, linear thru the mid range and if anything a bit, but not much, soft in the highs (something that helps sometimes with some bright sources).
BTW, re the KT88's, are you by any chance the same fella that Jim McShane is talking about in AudioAsylum who lost 4GL's?
BTW, re the KT88's, are you by any chance the same fella that Jim McShane is talking about in AudioAsylum who lost 4GL's?