Another update:
Channel Two:
JJ 5751 - I tried this in the V2 spot as an experiment in greater clean headroom. It does increase the clean headroom and gives a warmer tone to the channel. If your amp is brighter than you want, and you play a lot of clean, this might be just your tube.
It wasn't quite what I was looking for. Of all I've tried in V2, my favorite is still the NOS Sylvania. The new production Tung Sol sounds very similar to that. The EHx was a bit too bright for my tastes and a bit too gritty for my "clean" channel.
Channel One:
I had ordered some Soviet-era EF-86 equivalent tubes that finally arrived and tried one today in place of the Amperex bugle boy I had been using.
In Russian nomenclature this tube is 6J32P (In Cyrillic the 'J' is kind of like )I(, and the 'P' looks like the Greek letter Pi)
It's really a revelation.
I'd always found the tone contour control to be extremely subtle, and never felt the slightest need for the cut knob.
Now I notice a marked difference between each position on the tone contour, and I could actually reach a tone I felt was too bright, which I could not before.
The overall tone is the same - you'd immediately recognize it as an EF-86 tone - but it's just a bit grittier - kind of a fine-grained high end grit.
My theory is that the Soviet tube is a little bit brighter, so that when you start cutting brightness it makes more of an audible difference. In comparison, my Amperex sounds like it's already on the bottom two clicks of the tone contour switch.
It is a bit noisier - the first time I've felt the slightest justification for the EF86's noisy reputation - but nowhere near noisy enough to bother me. Also remember I live in a 58 year old house and play vintage style unpotted pickups.
You can get these by the crateload on eBay. I got mine from a seller called py_alexey
Yes, I know the o-ring on the bottom isn't doing anything