Replacing 6550s with KT 88s

If you are after a warmer, tubier presentation; you'll be happy. If you like your sound cleaner/less colored, stick with the Winged 'C' 6550. How old are your 6550's? The comparison(new tubes to older/worn tubes) might not be a fair one.

Mr P- Kevin Deal(Upscale Audio) sells both of those tubes. His testing, matching and burn-in procedures are second to none. The last set of Winged 'C's, that I purchased from him, lasted me over four years(at hard labor). I've since gone back to the(NOS) GE 6550A(at over five times the cost). I'm hoping that when that supply runs out, the Winged 'C' will still be in production. BTW: I wouldn't call the Genelex, "mushy." Just somewhat warmer than natural. Some systems are a bit threadbare, and can use the added color. Enjoy your music! (http://www.upscaleaudio.com/KT88/)

If you replace all of the tubes at once(pre and power); you won't know what tubes made what change, or to what degree. Just a thought: replace the preamp tubes first, and listen for a while. Put the old pre tubes back in, swap out the power amp tubes and listen for a while. If you are replacing the phase splitter and driver tubes: make that a separate/distinct step as well.

I had been purchasing NOS Sylvania 6550's, from Upscale, until his supply ran out. Went to the =C= and felt I was missing nothing(at that point). Those had over four years on them when replaced with the NOS GE 6550A octet. Thus- I can't offer a valid, direct comparison. It's my impression, however, that the GE's are a more dynamic, open & cleaner tube, than either the Sylvania or =C=(at the same bias setting). Once you have listened to your rig with the new compliment of tubes for a time: Try some NOS Siemens E188CC's or 7308's(direct replacement, identical in every parameter to the 6DJ8/6922), in your phase splitter and driver slots.

WOW- Singapore! I'll bet tubes ARE expensive over there. I've purchased quite a few Siemens tubes(in the past 12 years), from this vendor in West Germany. He's very reliable and sells excellent tubes: (http://myworld.ebay.com/audiotubes_de&ssPageName=STRK:MEFSX:SELLERID&_trksid=p3984.m1543.l2533) I started dealing with him long before he sold on eBay. Yes- Rolling preamp, driver and splitters is less expensive, UNLESS your tastes lean toward the pre-1966 Siemens CCa(I use six in my system), Tung-Sol CTL/6SN7GT round plates(two) and Sylvania CHS/6SN7W tall bottles(two). The sound staging, extension, air and liquidity of these tubes is addictive(and, YEAH- I'm hooked). I'm getting sick, just thinking of what will happen, when my personal stash runs out(OUCH). Looking forward to your impressions, post-swap. Happy listening!

I wouldn't be a bit surprised if brand new KT88s sounded better than end-of-life 6550s, of ANY brand, in ANYONE'S system. Happy listening!