tube amplifier auto bias- accurate?

I have an autobiasing tube amp (Primaluna) and it sounds fantastic. I'm all for this "gimmick". Sorry, all I can give you here is my opinion.

I have had two tube amps with auto bias, I have no reason to believe it didn't work- the sound was always fantastic.

Most auto control processes are as good or better than you can do manually. This would obviously be a requirement on the designer.

In airplanes, even little ones, the autopilot flies the plane more accurately than a pilot. This is hard for macho pilots (like me) to accept, but fuel consumption on a long trip proves the point.

I agree that auto bias is a good thing, I had very positive experience with the amps I owned.

As for tube testers, the B&K 707 or 747 are decent and can usually be had cheap at EBAY. Best of all they are transistor and need little or no calibration and won't drive you crazy with too many knobs to turn to get a reading.

Later, if you want a high end tester, the Hickok 752A is one of the best ever made but much more complicated.

A real easy tube tester for a beginner is the B&K 606. It comes in a small case like those portable 45rpm record players of old. Less options than the ones Albert is recommending, but it's smaller and can test a wide variety of tubes. I got mine in great shape on Ebay for I think around 50-60 bucks.