Best 845 tube out there?

I am running a pair of Cary CAD-211AE monoblocks with the standard no-name Chinese tubes shipped by Cary. Whilst I am happy with the sound, I think I should buy a pair of 845's to keep as backup in case something happens to these tubes.

Because I will need to buy FOUR of them, this rules out any tube that sells for stupid money (e.g. vintage RCA 845 tubes).

The only current production 845's I am aware of are:

- Shuguang 845 "standard"
- Shuguang 845B
- Shuguang 845C
- Shuguang PSVANE 845
- KR Audio 845

I have found reviews of the Shuguang 845B and 845C, but there is virtually no information out there on the new Shuguang "psvane" 845. Has anybody heard this valve, and is it a noticable improvement over the 845B and C? Also, what do people think of the KR?
Are the SuperTNT 845Ws(2008) the same as the Shuguang 845 Metal Plates(2009)? I have both and cannot tell any difference between them. Sophia Electric sells the 845 Metal plates online.

Has anyone tried the 845T at Grant Fidelity?
The SuperTNT 845W "Noblemen" tubes have the same tube rating/specs as the reference RCA 845. The Shuguang metal plate 845 has a lower dissipation rating (around 70w compared to the RCA standard of 100w).
Thanks all, that was very helpful. I can eliminate two candidate tubes straight off the bat - the Shuguang 845C and KR 845 are off the list because of incompatibility.

Someone mentioned the Sophia Electric 845. A quick google shows this:

Is the Sophia 845 a rebranded tube, or do they manufacture it themselves?

Brf, would a quad of SuperTNT Nobleman be as expensive as the other tubes (RCA, Amperex, etc).
Sophia does not manufacture tubes. These are re branded Chinese Shuguang tubes which have "passed" Sophia's quality control standards.

SuperTNT 845W Noblemens can be had for $400 pair when they are offered for sale, although, I have not seen too many pair for sale as most owner are keeping and/or hording them (like me)for future use or back ups. I like the Noblemens better then both Amperex and RCA. My favorite is still the United 845. I own all the aforementioned tubes including the Cetron 845 and a bunch of the Chinese variants.
The high dissipation Super TnT produced 845W are actually far rarer than any NOS due to the extremely small run which were produced.
They also sound significantly better in my amps.

I have an octet which will only be prised from my stiff cold hands !
I also have a quad of the superb high dissipation Super TnT 845M which were also produced in extremely low volume.

Don't confuse the above types with the inferior Shuguang variants which have perforated plates and are commonly found, also sometimes branded Sophia and/or Golden Dragon.

Other than the above tubes, unless you know the operating points of your amp and can adjust them, I'd suggest to stick to the standard Shuguang 845 B which is a decent sounding, reliable tube.
You may actually find that experimenting with different input & driver tubes achieves quite a pronounced variation in sonics.