In search for good tone-high gain: studio pre or other?

[j4q0]

I should get some new tubes and try them on the unit. As for now it seems that my L2 is not sounding as it should.
I believe JJ are well regarded as an option for the quad so I'll have to get me a set of those.

Should I buy them as a set so the store can give me a properly matched set? or is it really not that important?
I'm actually new to all this tube swapping thing so I'm afraid my experience in limited in this field.

 

[JMMP]

I haven't experienced much about brands or anything else, but I do know that preamp tubes do not need to be matched. Stick what sounds good where it sounds best.