and then check the current reading. So who cares if the tubes are "matched" at 250v or 350v, or if they are matched at 30ma.
What really MATTERS is that they are matched in YOUR specific amplifier running with YOUR specific characteristics.
The only way you can do that is to match them yourselves, with your own individual bias pot adjustment on each tube.
I have bought hundreds and hundreds of both "matched" tube and unmatched tubes in the past 20+ years. Matched tubes rarely match
unless you redesign the amplifier to match the matched tubes (by running it at a lower voltage and at whatever specific bias point they were tested at.
That not the optimum operating point for what you want, believe me!!
Call up any place that offers "tube matching" and ask them to give you the details of how they match. A few will be honest.
Most will tell you it's all computerized, and a lot of them will be clueless.
Another thing, for anyone (that's at least 80% of you reading this) that has a VTA driver board in their amplifier, take a look at the position of the bias pots
in your amp. If they are all set at about the same position (let's say 2 PM on a clock scale) then your tubes are matched!! If one or two tubes has the bias pots
cranked to some other position more than an hour away, they are definitely not matched.
This also becomes very obvious if you run your amp with a variac. Try running your amp on 100v instead of 120v. Check your bias readings.
Are they still matched?