Tube matching for the SF Line-3

How critical is tube matching? SF makes a big deal of it in the manual but I'd like to swap in some E88CCs (Teslas or Amperexes) that I have but which have not been matched.

go for it. your ears will let you now. i have alot of tube equipment. i change tubes all the time and i just listen to the sound,if ican hear that on tube is off. i try another. i admit i been told i have great hearing. go for it!
Hi Kal:

I had a lengthy conversation about this subject with one of the high end's more prominent tube equipment designers, and he said that, for line-level preamps, tube matching is generally not critical at all. He indicated that phono preamps with tube circuits can require a carefully chosen set of low-noise matched tubes, but that for other applications, the noise floor on small-signal tubes like those used in preamps is such that matching is definitely not necessary -- the only "matching" that is required is that they be culled for basic functionality within a general operating range.

Not to be cynical, but the micro-companies that manufacture the vast majority of the high-end tube gear make a good portion of their revenues from re-tubing sales -- my guess is that this is the best explanation for the advice in your SF owners' manual (SF, and now just Anthem, being a company that I otherwise have a lot of respect for, incidentally).
another thread about tube matching...sigh