KT150s in Audio Research Ref 110.

Is anyone using KT150s in the Ref 110 and what is your opinion please?  ARC told me that they weren't recommended but I've read differently.  I'm currently using KT120s. 
Those are some expensive tubes.
samzx12 OP895 posts08-13-2019 11:37amThose are some expensive tubes

Do you want the best? they will sound better than anything else, been there done that, as I mentioned.

Cheers George
For several years I had auto-bias integrated and power amps and I went through all the power tubes (and several small pre tubes). I ran El34, kt77, kt120, kt150, Kt88, 6550. I kept coming back to the El34s and the 6550s. At the time I had a pair of Spendor sp2/3s that the Sovtek 6550s sounded wonderful with. The Sovteks were new production and reasonably priced. 
George I understand.  Sometimes you have to pay to play. Been there with a  few tube amps.  From my understanding ARC ran low on 6550 tubes and the later production runs of Ref 110s used the KT120s.  
Moo foo how would you describe the differences between the 6550 and 120?