Anyone know how to bias output tubes (using built in meter) on a Stereo Knight M-40 (Int. Amp)?

Sounds like the meter acts as test point.Disregard RCA's for now.They shouldn't have anything to do with biasing.Try setting switch to #1,then slowly turn tweak(your word)next to tubes & see if meter changes.NOTE setting before moving tweak so it can go back.Pics in your link don't work.Maybe you could post pics in a virtual system so we can see it.

Thanks freediver. FYI - I'm a bit of an idiot, the amp is an S-40, not an M-40, sorry for any confusion.  I've set the switch to each number (1-4), with the amp on (its an integrated), with no inputs, and volume set to 0, the meter always reads 0. I also tried turning the pots (tweaks) next to each tube, but the meter doesn't move.  I'm thinking the RCAs are used to "insert" the meter's  "other lead", with the 1-4 switch being one, and the RCA's being the other.  If it's a true current reading, it'll need to be in series with the cathode, somehow they have to "break and insert" the meter in series. Perhaps the switch is set to 1 and RCA #1 is shorted?

Ok,Google turned up just enough info.I believe the 4 RCA's are so the passive preamp section can be isolated from the amp should you choose to use a different one.I think the problem is you must have a load on the amp to Bias.The single slot adjustment screws next to each power tube & the 1-4 switch should work together.First thing I would do is hook everything up & see if you get any sound.If your getting sound & the meter doesn't register it may be broken.Once you've confirmed the amp does work try the switch & bias pots,see what happens.Beautiful amp by the way.Good luck.

I wanted to elaborate on my findings re:the 4 RCA's on the side.First I am only about 70% sure that the info I found also applies to the S40 as it comes from the S.N.stand alone Reference PreAmp,which is the foundation of the PreAmp in the S40.Apparently when used as an Integrated Amp the S40 has an Active Class A PreAmp Stage.If I'm right the 4 RCA's are in to the Passive Stage of the PreAmp & out with just enough gain to drive the reference monoblocks they offered.Once you get the amp running you can test this theory.