The BEST system you've ever built !!!!

ARC Ref 2 Preamp
ARC 300w monoblocks
Lector CD Player (2 piece system)
McIntosh MR 78 with Modefferi Upgrade
McIntosh MPI-4
Magneplaner Tympani 1Ds
Valhalla interconnects and speaker cables
Square D 300 amp service... Wiring from main house electric service with 3 separate 20 amp lines ( #10 wire) to audio system
Square D Power Surge protection and line conditioner on each of 3 lines
Linn Sondec with supplied arm and Koetsu Onyx

It's what I built over the years...I cannot part with the 1978 Tympani 1Ds...my wife prefers these to the 20.1s

and most important component..the 16 by 20 Cathedral ceiling room with sprung wood 3/4 inch oak floors.

Mr Stark its a bit late to answer your question. In the sacred "Joe's Tube lore" they are described briefly. Anpther militasry Mullard only midrange and rolled of at the extremes probably only for systems that are harsh and would require taming.
I honestly was shocked by these comments. The only reason I have them is my tube Guru in England said stop messing aroud with the 6922s to me they all sound poorly and sonically their is not anything that really sounds different tube.
I thought my old friend had lost it I could easily hear differences poor lousy crappy and please don't go near me with tube again. He said there is one tube in the whole family worth anything it sound different nd is just bettter . This CV2943 he had none to sell but tubemonger had several sub variants It was not muddied and rolled off. Absolutekluy it fell into the clean deatailed category. Finding a matched quad of NOS these were NIB and still had cihgar rolls around them. I had to get them from Sweden. The price was not my idea of a good time but I saw everything in a 6922 with a good reputation cost the same and even a lot more. These tested stronger than new nominal but was only pretty certain they were True NOS. I saw them I said if that isn't as pristine as I had ever seen then their is no NOS. My 6SN7 guy Len had since eclipsed the perfect period box packing and yes the tubes.
You can find them at Kevin Deal's store in mediocre comdition but if you got the moola it is a must try

Proac Response 2.5 DIY clone. Sonic frontiers line 1. Mark Levinson ML-9. Level 1 Mod (parts connexion) Jolida JD-100. NOS TUBES THROUGHOUT, Amperex, Brimar.

so real

Pre: Sonic Frontiers Line 1
Amp: Sonic Frontiers 2 x 110w (can't remember model)
Source: Sony NS999ES SACD/CD
DAC: Meridian (can't remeber model)
Speakers: Wilson Cubs on Sound Anchor stands
Spkr wire: Audience Au24
I/C: Transparent Link 100 RCA
Transparent AES
Goldmund optical
Sub: Sunfire True Sub (the original model, not the current inferior model)
PCs: all stock
Power Cond: PSA Ultimate Outlet and Richard Grey somethings
StanDesign isolation racks
Room treatment: something that looked like small pillows

My current system is the best by far.

I started focusing in on optimizing what I had to get to where I am now about 2 years ago.

Practically, at this point, the only interest in changing anything I have is possibly:

1) a higher power, higher current SS monster amp in the future to really take the big OHM f-5s to their limit.

2) Trying a pair of very high efficiency speakers, like horns, other dynamic designs, or even something totally radical like Emerald Physics maybe. I'd probably have to sell my Dynaudios to do this though and am not ready to part with them yet.