Cary SLI-80 Signature - Tube Recommendation

Hello Audiogoner - Please Advise/Help......THANKS....
Currently, I own a Cary SLI-80 Signature integrated amplifier and would like to try on a new/better tube. My price range is $50-$75 per tube. Please note this is a older model, it's about 6 years old.

1 - Rectifier Tube 5u4g (??????? I have no clue about this)

2 - Input Tube 6922 (I got Amperex white label, any other recommend ??????

3 - Power Tube 6550 - (Genalex Gold Lion KT88 tubes Valves 6550, any other recommend????????????

4 - Output Tube 6sn7gt - (??????? I have no clue about this)

Please help, I would like to hear from you for your recommendation............BIG THANKS.......

That's a tall order.
For 6922s I use a Mullard mil spec tube which is distinctly un-Mullard like. It is not warm at all but rather like German tubes, they have a unique designation E88CC-01. It is called CV2943 note these are different than the CV2942. It is occasionally for sale at Upscale. I would call Mr. Deal and see what he can do. OTOH The Amperex are darned good so there is no need to run out and buy expensive NOS tubes IMHO. The CV 2943s cost me dearly the last time I got them. (Tango Tubes in Sweden)
If you have KT-88s in there, that are the Genalex reissues, that is as good as it gets, outside possibly of the ever rare NOS Tung Sols and such. Therefore leave them in or get them, if you don't have them yet.
The rectifier is something I defer to others who use them more than I do.
The 6SN7GT is not an "output tube" as a rule. They are preamp tubes used initially as vertical hold tubes in early TVs, but had been used since they were introduced in 1939 for a wide number of applications due to its inherent linearity. I like them for preamps, as does Cary. The GT is the earliest incarnation, which provides for the least voltage on the plates. There are a number of resources to turn to- if you can find Bent Jesse's tube site, that might help you. He has a lengthy description of the various 6SN7s because he sells them. I have no affiliation or financial interest in his business.
here is a good resource for data on 6SN7's, and their charcteristics: ( If you desire clean, accurate sound(no added warmth): find a pair of BOTTOM GETTERED Ken-Rad JAN CKR or Sylvania JAN CHS, VT-231/6SN7GT's(NOT GTA's, etc), from the 40's or 50's. ie: ( ( They both perform very closely to the Tung Sol 6SN7GT round plate, and Sylvania 6SN7W regarding faithfulness to the signal, sound staging, imaging, etc. For a bit of added warmth(ala the Amperex small tubes); the National Union and RCA VT-231's(same era) are nice(same construction as shown in the pic). None of these will send you to the poorhouse, even for the closest matched pair of NOS tubes. SHOP CAREFULLY!
BIG THANKS to Mechans & Rodman99999
Pretty sure your comment is very help and interest on my research.............Thanks again......

Anyone out there has a good tip about rectifier 5u4g tube section on this Cary gear????????? NOS of RCA, Sylvania, Raytheon, Ken-Rad ????????Please advise.....THANKS...
Mullard rectifiers have always given me the most enjoyable reproduction, and longest life(by far). ie: (
Mullard 5U4G is a very nice choice. So are Tung Sol 5U4G Coke Bottles for a a lot less.
NOS Tung Sol