#1
What would I benefit from replacing the tubes in my VK? The cleans seem to break up easily when i crank the amp; would I get better cleans at high volumes? Would new tubes change the overdrive tone?

Would a new speaker be a better idea? If so whats good in the speaker world?

Also, what do I have to do to swap the tubes? Is this whole biasing thing necessary?

thanks,
My Gear:

Fender 62 RI Stratocaster
Epiphone Les Paul Standard+
Fender Supersonic
Boss DD-3 Delay
Boss OS-2 OD/DS
Martin 000-28
Washburn D10s
#2
Yes you would benefit, change the speaker before the tubes though.

What styles do you play?

If you changed the tubes to improve the cleans chances are the overdrive will lose gain. I don't think biasing is necessary on these amps but i'm not too sure.
Schecter C1 Classic Left Handed
Line 6 POD HD500
Peavey Valveking 112
#3
I don't like the tone of the overdrive, i mainly use pedals, or the od channel for slight gain. play mostly rock & alternative.
My Gear:

Fender 62 RI Stratocaster
Epiphone Les Paul Standard+
Fender Supersonic
Boss DD-3 Delay
Boss OS-2 OD/DS
Martin 000-28
Washburn D10s
#4
I've heard JJ's are good (6L6) and Tung Sol 12AX7, in fact, I ordered some a little while ago so we'll see how they go, then I'm gonna' upgrade the ol' Speakers to either Swamp Thangs or Vintage 30's