Hi Drjoe,
yep, Spectral and MIT all the way (speaker cables 770 Ultralinear 2 and interconnect (unbalanced) Oracle 3.1). Not really a high pitched hum as a low pitch rumble... With nothing attached than the speaker cable is hums, with interconnect attached the hum increases.... But as stated, connected to a different (out of the listening room) grounded AC outlet, the problem is almost gone. Got to have an electrician to have a look at this. Maybe shift the amps away from the converter? Read that this might also help... Keep you informed of progress. Again, thanx!!