I've been playing around with tubes over the weekend.  My amp has the effects loop buffer built-in.  Having said that, I found the best results to have the same brand tube in the V1 and also in the effects loop buffer.  I put one of my Amperex tubes in V1 the other in the loop buffer.  Put my JAN GE 12AX7WA in V2.  Left the Chinese in the phase inverter and wow! 

Anyone with a C-lator have similar experience?

I also put the SED "Winged C" tubes back in and set the bias to ~28mV. 

How do you guys bias your output tubes, and what do you set them to typically?  I recently picked up a bias tester that plugs into my Fluke multimeter from amp-head.  You can buy these from weber unassembled.  But for the small amount more, I picked up an amp-head mV version.

I also tried a set of Tung-Sol NOS 5881s in my amp.  They sound good!!!  But I'm saving these for my tweed Bandmaster.

Can't see the pictures but I know this circuit!!!   Sounds amazing.  The originals had 3 Jensen P10R speakers connected in a series (not parallel).

These are long plates, brown lettering, and have an 8 sided box with 12AX7 printed inside on them (just like RCAs but larger).  They also say Made in Japan on them.  I just searched eBay and only saw green print sylvanias.  But these are amazing tubes, and not very well known.  I stumbled upon them accidentally when I bought 4 ANOS RCA tubes from a reputable dealer and this was one of them.  The silkscreening had rubbed off quite a bit on the original one I purchased but after getting a bunch of the Baldwin tubes (yellow, green, and brown print), I found out they were MIJ.

These are my second favorite V1 tube.  I'd highly recommend trying one when they show up on eBay.

I don't know why the chinese sound best to me in the PI.  They just sound great and strong in there.  If I didn't have these two Amperex tubes, my second choice would be this Baldwin in V1 and a JAN GE 12ax7wa in V2.  JAN Phillips 12ax7wa sound nearly as good to my ears in V2 but slightly different.  They look identical in construction.

Any chance we'll see a ceriatone (or mods) with a buffered loop and a reverb circuit?

Here's my .02.

V1 - Amperex 12ax7
V2 - Amperex 12ax7
V3 - Chinese 12ax7ac (TAD, Ruby, whatever).

Powertubes.

SED "Winged C" 6L6GC-STR
TAD 6L6GC-STR
JAN Phillips 6L6WGB (early breakup with these).

Other contenders..

V1 - Baldwin Japan 12ax7 long plates (find them usd on ebay, very musical and rich).  These sound better than the RCA 12ax7s I have..
V2 - JAN GE 12ax7wa

Others I've tried..  Ei - 12ax7(ecc83).  A little brittle.  Sovtek 12ax7 - OK not great in V1 - no way in V2 on the Sovtek.  GE 12ax7 grayplate good in V2. 

Phase inverter... only tube I've found that I care for is the Chinese 12ax7s.

Amperex (holland, short plate) is the hands down winner in both V1 and V2 in my book.  I have a D-style amp, but not a ceriatone.  YMMV