KT 170

I've had them for about 400 hours now in a primaluna evo 300 power amp. Not much increase in power (PL is a little to gentle on them, I think they might like to be driven a bit harder) but a discernable increae in control of the speakers (dhalquest dq-20's are behaving very nicely). Best way to describe them is as a GL kt-77 on steroids. Not the ones that make you grow hair, the ones that make you all sexy and stuff. Or something. Just not hairy.

It's very linear and tight with wonderful bass - very SS like in that regard but you won't mistake it for SS - at least not on my system but dayum, is it frigging nice. Very nicely extended highs and a surprisingly pleasing midrange to boot.

I really like it.  

NOS amprex in gain stage and NOS sylvania in driver stages. 

"I've had them for about 400 hours now in a primaluna evo 300 power amp."

Interesting news stickmon. According to johnss, he contacted PL and told they wont fit.

This has my buy now finger twitching.

They hit the xformers on any PL that uses 8 output tubes.

I contacted upscale audio a couple months ago about them: "We’re testing, buy kt-150’s". Screw that, you advertise as "future tube proof" so we’re gonna test. They are :)

EDIT: total cost for the 170's from viva tubes was 20 bucks less than 150's from upscale. Sure, it isn't much but thats 2 good grams of (legal) weed here.

"They hit the xformers on any PL that uses 8 output tubes."

stickmon42-
Is that what Upscale told you? Tubes contacting  the Xformer case seems like a concern. I have the HP=8 

That's from the Facebook PL group, think someone measured and verified with upscale but it wasn't me. I have no way of actually verifying if it's true or not but it would be a major concern. 

All I can say for certain is that they work extremely well in an evo 300 power amp.