Rolling KT150s in Primaluna hp integrated

George maybe you're right but then again maybe if the tube goes through the cryogenic process one may well end up with a better tube for having survived. This would be providing nothing before and after changes with regard to measurements and vacuum leakage. All I can say with any certainty is not so much about whether it works or not only that the cryoed tubes sounded better, CLEARLY. I have read some of the debate and controversy concerning this issue, seems more nay than yeah at least with regard to tubes. In my case it very well may be that there was more miles on my original KT150s than I realized and that putting in fresh tubes made the difference and it had nothing to do with the cryogenic process. I have to find out the parameters to test all the subjects (KT150s) on my Hickcock to see if this might be the reason or at least give me a clue. 

If your amp can run 6L6 tubes, it would be interesting to try some vintage tubes of this type.  While they don't deliver much power, I really like the sound of that type of tube.  I also like 350s, but at close to $1,000 a tube, that experiment probably will not get off the ground.

Larryi,  If only we were billionaires!  I'd finance that experiment now!

The Tung Sol 7581A is a very very good tube.  

FWIW, I briefly replaced the Tung-Sol KT120's in the CMII, and rolled in Genelex Gold Lion KT88's.  Perhaps they were slightly sweeter, but I missed the greater authoritativeness of the 120's.

I’m approaching 2 weeks into this tube roll and I have a better understanding of what the KT150s do.

The KT150s in the PL Dialogue Premium HP are a great match. It’s not easy to go back to other powertubes. I had to for a day as I dropped one when taking it out. In this amp (in my room, etc.) the KT150s just sound better. The power allows imaging and soundstage to be bigger and more controlled. The bass is without question more robust and controlled than I’ve ever heard with tubes or with 2 SS integrateds with my speakers. 

While I can’t say what others would like, I can certainly say that rolling KT150s in this amp create a big change. It’s really something owners should experience. I think the change could keep me out of the upgrade game for some time as it’s made such an improvement in sonics.

Using a combination of Mullards and Ciftes 12AU7s in the first four slots with the KT150s really dials things in to my liking.

What’s kind of surprising is the KT150s are not edgy, harsh, bright, etc. They just add more dynamics, control, authority, size and precision to imaging.

If anyone wants to buy a matched octet of Gold Lion KT88s, which I purchased from Upscale (not cyroed), PM me. They cannot have more than 300 hours on them as they are less than a year old and I ran them in rotation with 7581As, 2 types of EL34s, and now the KT150s. Such a great tube that I don’t think I’ll use with moving in the KT150s.