Stock, it's okay. In my opinion, Sovteks are a little harsh in this amp. Drop a JJ/Tesla or Electro-Harmonix 12DW7 in V1, the first triode's got a gain factor of 20, like a 12AU7, while the second triode has a gain factor of 100 like a 12AX7. It buys you a little headroom, and makes it a little more useful for playing at home. Get a JJ/Tesla EL84 in V2, and it gets even better - the JJs just have this warmth to them that really brings this amp alive. With a few simple mods, it gets really tasty, but I'll cover that in a minute.
This amp responds well to pick hand dynamics. If you're competing with a loud rhythm section, don't expect a lot of clean headroom. At more moderate levels, it cleans up nicely. I also find it works well with pedals.
I'm not 100% certain of how I feel about the stock speaker in the matching cab, but this review is about the amp, not the cab. I've ran it through a few other cabs, they each add their own element to the overall sound.
This thing eats power tubes and runs hot. After 6 months of overheating, several of the resistors smoked.
Drop R1 (input grid stopper) from 68k to 22k, this puts more guitar signal to the grid on the first triode. Replace R3 & R4 (V1a & V1b plate resistors) with 100k, this gets your plate voltages closer to what they should be. I swapped R6 & R7 (voltage divider/grid stopper for V1b) to 500k, this changes the way the first stage drives the second stage. Fine-tune dissipation on the EL84 by increasing R15 (V2 cathode resistor) to 270 2W, and increase R10 (first resistor in the power supply filtering section) to 1K 2W to lower B+ plate supplies. The Rev3 PT has multiple taps on the primary for international voltages: BLK=0, WHT=100, YEL=115, BLU=230, BRN=240. Stock uses Black & Yellow, switch them to White & Blue for a 130V pair. That should improve tone, bring your B+ down and get the EL84 within specs.
Usual disclaimer applies - it's a tube amp, the voltages in there can kill you. If in doubt, BRING IT TO A TECH!
In terms of construction, they did good. Chassis, cabinet, hardware and such are great It's simple, it's solid, it's well made - the real issues are in the circuit design.
I really like this amp a lot, $10 worth of resistors from DigiKey and $25 worth of tubes from the bay really make it juicy. There are other amps I like better, but for the price with some easy tweaks, it's a no-brainer.
Would I do it all again? Yeah...as irritating as the failure was, fixing & fine-tuning it was fun, and it's good at what it does. Oh, yeah, I almost forgot, grab a Gretsch 5120, slap an overdrive and a delay in front of it, and you've got blues & rockabilly heaven!