Amps with meters ...

For an admittedly prototype 833-A SET and a GM70 SET for the center channel I put in milliampere meters between one side of the cathode and ground to know what kind of condition the tubes are in. This is simpler than power output meters the McIntosh uses. If you want to defeat the lighting in the meters it would not be difficult to find one wire to the lights and insert a switch. McIntosh will supply you with a schematic and maintenance sheet to help you see what wire to interrupt.I do not defeat the purple LED lighting I put in my meters because the 833-A cathode at 10 Volts, 10 Amps is, in effect, a 100 Watt light.

With your eyes closed, green ketchup tastes the same as red ketchup.  Open your eyes and it doesn't.

I have an ARC GS150 with meters. But they are linear and don't move at all at lower levels. They should be log meters, like what Mac uses. But the printed scales on the meters are log. I told ARC about their error but they ignored my comment

Or consider amps with incomprehensible meters.
The Marantz SM-11S1 has an enigmatic porthole, front and center in the faceplate that contains a digital numerical read-out that constantly varies in values and, for the life of me, I can never fathom what it is that Marantz expects people to get out of this tech for tech's sake.  Useful information is the last thing it provides.
OTOH, I totally love all other aspects of this amp, especially the sound quality and bullet-proofness of build & operation.  

Gregj, perhaps your letter wasn't threatening enough.

Anodyne, you need to enjoy the incomprehensible and enigmatic, not question it. Mr Squires certainly doesn't and look at how many of us have responded to his thread.

Grasshopper