Kt-88's for ARC amp

I need a retube and a tech-tube supplier recommended that I try this tube. He's says it's much warmer sounding and musical compared to the 6550. Have any of you tried this tube in your ARC amp?
I do not own an ARC amp, but if you would like some expert advise on tubes and tube questions, contact Jim McShane. I purchased some KT88s from Jim for my Audio Space amp and he is very helpful. jimmcshane@prodigy.net
Ask ARC. I don't own your amp, but I did own a predecessor. They used to have reservations about using KT88's in their amps in general. I believe because they didn't want to have to pay for damages caused by poor replacement tube selection by customers when the amp was still under warranty. Part of that had, I believe, to do with KT88 reliability and the consequent damage that poor ones could cause when used in their amps, but part of it could have to do with the design criteria of the amp. Some high power amps can eat less than very rugged KT88's. I've got a couple of those. FWIW.
I have A CJ amp that uses 6550's. I called CJ to ask if I could use KT88's and they did not advise it. I was told that I would have problems biasing the tubes. I would check with ARC to insure that your amp wouldn't have the same type of problem that I would have faced.
FWIW, This is what Kevin at Upscale says about putting KT88's in a specific ARC amp.

"ATTENTION! We are no longer re-tubing Audio Research VT100 amplifiers. Mk1, Mk2, Mk3... doesn't matter... no exceptions. "
I know all about Mr. Deal. I think his name should be Mr. NoDeal.
Taters, call ARC. They will not lead you astray with your amp.

Maybe you should go for a nice SS amp. It seems the tube playground has too many peripheries you are not ready to "deal" with.