How Important is Tube Matching?

I was wondering how important tube matching is for a preamplifier. I had read somewhere that tube matching is extremely important if the tubes were used in an amplifier but was less critical for the preamp. Is this true? I've recently acquired a tube preamp and want to upgrade the tubes but wasn't sure it was worthwhile to pay the big dollars to get matched set(s)...It's a six channel preamp! Any advice would be appreciated.
Thank you!
in most cases preamp tubes work in small signal operation with large dynamic margin. therefore they needn't be matched to each other.
in some cases with high gain tube preamps you might need to match them so i suggest speaking to the manufacturer first.
They are not required in some preamps at all because each tube has aspecific role in in an active gain stage that drives both cjannels this is absoluteley certain for my legendary ARC SP6B. It is not going to be true in cases where each tube is in a circuit that drives a differet channel unlesss they give you explicit instruction in adjusting the voltage to each tube to get te same gain in a multi channel multiple tube preamp. I doubt that you will be able to do it so. I would get well matched tubes. If there is only one gain stage for all 6 channels do what you like but don't use the wrong tube type.
The preamp I own is the Copland six channel CVA306. There are six tubes (one for each channel). Based on your feedback, I'm assuming that it's probably important for me to get at least a couple matched pairs (for front l/r...and rear l/r). The center and sub channels are probably less critical. Does this sound right???

Thanks again,
You're wrong.

Preamp tubes don't operate peak to peak. Moreover they often have a large headroom to reach such. Therefore no matching is required.
Don't spend extra on that.
Do you know how to bias the tubes? If so, don't worry about matching the tubes. It's primarily each channel's L/R that has to be balanced -- which it is in yr Copland (it's one tube)
The preamp tube(s) you will benefit from having matched triodes within the twin triode tube itself are the driver tubes. They are responsible for splitting the signal into two 180 degree halves and sending the resulting split signals onto the power amplification stages. This of course is push-pull configurations.
To make this issue(small signal v.s. large signal) more clear first I'll make some definitions:

Small Signal operation is when the tube or transistor operate in the most linear region and never even near peak values.

Large Signal operation is when the tube or transistors operate peak to peak or close to it.

Unmatched large signal tubes will likely have different peak values.