Depends on what you mean by 'matched'.
If you mean 'two tubes of the same manufacturer that are elctrically identical (tested/matched)' there are a few high end balanced preamps which will benefit, but will still run if the tubes aren't perfectly matched, but not optimally. Most pre-amps do not need to have 'matched' tubes.
If you mean can you mix brands of tubes of the same type, for example using a pair consisting of one EH12AX7A and one JJ12AX7A, the answer is yes, but its highly likely that you won't like the sound. Tubes brands and types have different sonic signatures as well as gain. It would be, sort of comparable to using two different brand mono amps, or even the same brand with different ratings. Why would anyone want to do that?
Hope that helps a bit.
If you mean 'two tubes of the same manufacturer that are elctrically identical (tested/matched)' there are a few high end balanced preamps which will benefit, but will still run if the tubes aren't perfectly matched, but not optimally. Most pre-amps do not need to have 'matched' tubes.
If you mean can you mix brands of tubes of the same type, for example using a pair consisting of one EH12AX7A and one JJ12AX7A, the answer is yes, but its highly likely that you won't like the sound. Tubes brands and types have different sonic signatures as well as gain. It would be, sort of comparable to using two different brand mono amps, or even the same brand with different ratings. Why would anyone want to do that?
Hope that helps a bit.