Matching output transistors

[Axtman]

What is meant when people talk about matching output transistors? Do they mean gain (hFE)?

I know not to mix different manufacturers and/or equivalent transistors on the side of an amp. What about mixing date codes or shall I stick with the same batch?

[g1]

Hfe and Vbe should both be matched. That ensures they idle the same when setting bias, and they track well with each other through the signal range.
More commonly seen in higher power amps and with mosfets.
If you want to do your own matching:
https://sound-au.com/transistor-matching.htm

[Tassieviking]

I use a very cheap tester from Ebay.
Just search for LCR-T4 and you should find ones similar to mine, it can test all different transistors,FET, MOSFET, diodes, capacitors, inductors, resistors etc.
I really love that little tester, you can get better versions that come in a housing already. (I ordered a plexi case for mine)