I'm looking at buying new valves/tubes for my Peavey XXX. I want to improve the cleans and headroom but keep the gain on the crunch/ultra channels.

Would anyone recommend some? I was looking to switch from 6L6's to EL34s which is supposed to improve the cleans/headroom. Has anyone tried this? And what pre-amp valves would make a difference? I've heard changing the phase inverter has a big impact on headroom.

I have the Peavey 3120 (AKA XXX).

I really like the El34s did not think I would like them as all my other amps have 6L6's in them.

But to me El34s sound so much better in the XXX then 6L6's do so I put the El34s back in.
JJ's. They'll balance out the brightness of the amp nicely.

I wouldn't recommend EL34's, unless you know for a fact you want them. I personally prefer them in that amp, but they won't get you better cleans - 6L6's are better for that. EL34's will get you warmer cleans, more lively cleans, but they won't actually be cleaner, if that makes sense.
Spin 'round carousel when your horse isn't screwed in.

My band:
Fractured Instinct
(For fans of Death/Groove/Prog Metal)

Ibanez RGA42E
Ibanez S420
LTD H-301
Ibanez RG520
Peavey Predator USA
Douglas Grendel 725
Line 6 Pod HD500X