Solid State Preamp to replace tube unit

@jimbones Not sure how far away you are to ship it in - I wonder why you might not consider sending in your current preamp to CJ for a checkover. Maybe they can test, check, make recommended updates?,

My main system is all tube preamp / mono tube amps. I had been searching past few years for a ClassA Pass/Forte’ F44 preamp to match my Pass/Forte 3/1A Class A amplifier in my other system. Found one, have been trying it on rotation this year. Sounds nice for sure. When I swap back in my all tube preamp with the Class A solid state amp there can be this added layering and 3D dimension effect that occurs. I credit the 6SN7 tube preamp. Has its own sound like your CJ gear. Swapping back and forth between the two different types of preamps helps to realize the differences. FYI, I’ve chatted with Nelson about this SS vs Tube preamp topic some a few years back. As I understand it, it’s one of the reasons he came up with the Korg B1 flat tube DIY preamp kit. It offers an option to explore for Pass amp owners. I’d be curious to know if CJ can help you or not to investigate more.

@coppy777 Last time I spoke to Jeff was about my Power Amp tubes. Jeff is a funny guy (not ha ha funny) I think I caught him on a bad day. Seemed temperamental. I had asked if I can put KT120 in my Premiere 12 and he said "absolutely not" Yest he has specifically told other P12 owners it is ok to do so. I am perplexed. Anyway back to the pre, I am going to go with the recommendation that he told another CJ owner about the Philips tube. So far the Tesla sounds amazing, definitely the best I have heard in my system so I will definitely be buying another one for my stash. 

@jimbones do you have a copy of your original CJ owners manual for your version/series/serial numbers of the Premier 12 amps by chance? I’ve run across this same type of KT120/KT150/KT170 tube use confusion [with other manufacturers] about when you can/cannot run these larger output tubes where [for example] later versions might have had the larger power and output transformers to support the larger output tubes. Sure they might work and play, however is Jeff possibly referring to potential damage that might occur for your particular amps and serial numbers by chance - worth reconfirming. There may be a reason he said no.

Found this on the CJ forum, yes, some are running KT120s in their Premier 12s. A friend of mine has Premier 12s and still runs the 6550s in his fwiw. https://conradjohnsonowners.com/viewtopic.php?t=2320

@decooney yep I initiated that thread. Jeff did not ask me the serial numbers and as far as I know there was only one version of P12. Unless you sent it back to the factory specifically for the Cap upgrade. He does not change out the transformer in that upgrade. In fact the guy I bought the amps from ran it with KT120's in it before he sold it to me!! For some reason I am a bit nervous about putting in KT120, my luck the unit will blow up lol

Different output tubes will certainly sound different but will not increase the amplifier's output. The same energy in produces the same output.  KT 120s can replace those tubes but as you get to the KT150 and especially the KT170 the electrical requirements of the tubes are enough different that unexpected things might happen in some circuits.  So change them only for the sound difference, not performance enhancements.