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

Thanks Peter, good idea.  Here's a url with photo's and detailed description - except how to bias.
http://www.stereoknight.com/S-40.html

Thanks freediver for responding.  There are tweaks next to each tube (4), and there's a switch on the side to select 1 thru 4 (tubes, I'm assuming), it's currently setting on 4.  Then, there's a removable plate, next to the 1-4 switch, behind it has four RCA connectors, labeled 1-4. That's what I got.  The meter is definitely for biasing, it's inside the cage, and calibrated in mA, 0-100 mA.  So the switch surely connects the meter to each tube, but I don't know what to do with the RCAs.  I've measured them. with power off. Grounds are ground, and the plus lead reads 10.3 ohms.  Kinda sounds like a cathode biasing resistor? But who knows?  This is a ZERO feedback amp, and it sounds unbelievable.  It set new standards for me, and made most of my other amps crappy in comparison. Gotta keep it running!!! Let me know if you can help.

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?

Hi Freediver. A little reset here. The amp works great. The sound is absolutely amazing. I have several tube amps, but none with NO negative feedback...this thing really sings...it's ...in my world..unbelievable.  BUT...I don't know how to get the meter to engage.  The RCA's are not preamp out - power amp in.  They are four RCA's with open connectors.  No shorting straps. They are part of the biasing scheme, could be a short when applied, or maybe some resistance??? I believe the amp must of had some biasing fixture that plugged on the appropriate RCA of the tube you are biasing. 

I did do all the testing of the 1-4 switch, with the amp under load, but no input, and volume at 0.

The S40 is an active preamp (class A) feeding their KT88 tube output in what they call class A push-pull. (???) In my world, all push-pull is class AB by definition, but???? I can't argue with the sound of this amp. Just need to know how to keep it working.  I may have to buy a KT88 biasing socket.

Congrats aasbakk, you have found a great amp.  I didn't know anything about StereoKnight or the S40 when I got mine, but after having it for a decade, and having bought several other amps, I do know now, how special this amp is (still have it, probably never let it go).

Sooo... I did some digging to find out how to bias it.  I discovered one of the two StereoKnight principles (the tech guy), started another audio company in Australia, and I was able to find out from him how to set the bias. You do use the four RCA connectors that are behind the little square panel on the left side of amp. Each RCA connector correspond to an output tube. The RCA connector is used with an external voltmeter.  RCA + connects to meter +, RCA - connects to meter -.  (Note: the built-in amp meter does not work on the S40 - it's not even wired - I looked.) Basically, the RCA connector lets you connect a voltmeter across a 10 ohm (cathode resistor). The bias specification is 45ma, so 45ma across the 10 ohm resistor produces 450mV.  This is what you'll read on the meter, 450mV or .45 volts.

So the bias steps are; 1) Hook up voltmeter to RCA connector #1 (to bias tube #1 - tube furthest right) 2) Turn on amp with no input signal, volume at 0. Let tubes warm up for 5 minutes, and take measurement on meter.  If not 450mV, use the tweak (potentiometer) next to tube #1, and set the voltage to 450mv. 3) Turn off amp and move voltmeter to RCA #2, and repeat.  That does it.

Hope you enjoy your amp as much as I've enjoyed mine.  I'm currently running a set of Gold Lion KT88, NOS Mullard E188CC, and NOS Amprex 7316. Man-o-man does this thing sing!  (FYI - Good NOS tubes in the front end really made a difference.)