AFAIK the only big tube producer who AC-matches is Groove Tubes. b) you really need a huge quantity of 'raw' tubes to end up with a worthwhile number of AC-matched sets, and c) it doesn't always result in a closely-DC-idle-matched set, which can greatly increase the WTF!-factor on resale, especially when top dollar was paid. Getting a set of tubes that makes music in an identical fashion is very much a worthwhile goal IMO, but hardly anyone does it because a) it's difficult to do without a curve tracer, which involves money, possibly a computer w/attendant skill set, etc.
Idle DC-matching is really quick and easy to do, and it gives a number that can be readily checked with a meter - but usually it doesn't last, and unless you've got a serious mismatch (which IMO is important mainly for indicating large differences in baseline tube transconductances, which can make a real difference) it really isn't a matter of life and death tone-wise my $.02, YMMV.ĪC matching - now that's a different story.
DAMMIT RAY FULL
In fact, I've seen sets with much greater idle mismatches that put out very similar full-power currents, and sounded great I'd trade DC current-matching at full power for DC current-matching at idle any day of the week, but I don't know of any tube seller that does this (and what is "full power"? or "idle", for that matter?). Unless you're using a toroidal OT - in which case a bias-servo circuit is in order IMO - 5mA or less DC mismatch won't matter at all IME.
I realize you probably won't give a damn what I say but IMO it's quite possible to have a truly matched tube set in a musically-important way (not merely in idling-heat-output) that nonetheless shows significant variances in DC current flow at idle between tubes.
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