what to think about when matching pre and amp

im new to tube amps. i hear one have to think about sertain things when matching a preamp with an amp. is it the sensitivity or.. as an example im thinking about buying a Conrad Johnson ls17mk2.. and i can also get a CJ premier 11a. how do i know they match? these would probably match since theyre the same brand.. or..can i think that way. please help
They will work just fine together.
thank you. but how do i know that? if i had not already chosen CJ units.. say i have chosen an amp, and are looking for a preamp to match.. what do i have to look for?
Lots of things to look for/at. Among the things that you may actually FIND (i.e. the manufacturers actually disclose) are
pre: output voltage, nominal output impedance & highest, input impedance
amp: input sensitivity (voltage for full power), input impedance, bandwidth.

Unfortunately, you'd still have to listen to any pre-power combo to come to definitive conclusions! Cheers
You will never find enough information to really "know." All you can do is try and see if you like it. Don't get hung up on the numbers because what you need are curves which no manufacturer will give you.
ok, thanks. deep down i was really wondering if i would wreck something if they dont match in some way
I use the CJ 17 with a Pass lab Aleph 3, which is supposed to be difficult to match because of input impedence I think, no problems. I agree with gregm, if it works, who cares if it should'nt be a good match.