Doepfer

I have an A-137 and A-110 in a DIY #1 kit, mounted in a wooden case. 
For power, it uses a 120v->16v AC adaptor, that has two wires going
into the DIY #1's power supply, then it goes into the power bus.  I
don't have the proper mono wiring yet, but used some 3.5mm stereo
patch cables to patch some stuff through the 137, and also ran the 110
into the 137, just as a test to see how it sounds.  And there's a
noticeable hum on this thing.  I'm not at home right now, at a buddy's
house playing with the thing, so I don't know if it's maybe just his
power.  Otherwise, it's either the stereo cables (I don't see why), or
this thing just has a hum problem.  Could it be because it's not
grounded?  Any suggestions?


Also, once I get the A-110 and A-190 hooked up, will it be playing the
right notes when I hit a key?  (are they somehow tuned at the
factory?)  Or is that what the tune knob is for on the front?  Thanks!