What style are you looking to play too?
If it's more the heavier/high gain stuff then the Valve king NEEDS a tube screamer or a some sort of boost in front of it running pretty hot, 'cause this amp doesn't have that much gain as normal high gain amps. The cheapest Tube Screamer that works well is the probably the
Ibanez TS-7. It has a similar PCB to that of the
TS-808 with just two different resistors.
But the amp should work fine for other genre's. Unfortunately I haven't really paid that much attention to the clean channel so I can't comment there.
As for the cab, I'd suggest rather get one GREAT sounding 2x12 (for either a little bit less or a similar price) than a mediocre or less than average 4x12 'cause...well...the 4x12 just looks cooler on stage 8).
The info on the cab says "Loaded with Celestians" which isn't normally good as they're not being specific but better than standard stock speakers. If it was good they tell you exactly what brand and model etc
Don't worry about the 2x12 being less loud too. Besides the difference being dismal, you
probably wouldn't crank the 4x12 louder than you would the 2x12 anyway.
At the moment I have a 4x12 but want to buy a 2x12 cab just for it's convenience.
Cabs (depending on your budget):
MARSHALL TSLC212
ENGL E212VH (great cab ?)
FRAMUS FR212 CB
LANEY GS212IE (GFSA user "dylan" has this cab but custom made for him with V30's in them)
FENDER 212 SUPER SONIC BOX BLONDE/OXB (I've played this cab and probably would again)
ORANGE PPC212COB
ORANGE PPC212