Hum in ARC Ref 3 not on 0 but 1-103 light buzz

Tubes can be imperfect beasts no matter the duration of use on them. It sounds like a bad tube, which will get worse. I would also like to add that I had nordost SPM interconnects running from my power amp to my subwoofer and I was hearing a tremendous amount of hum. I removed the SPM's and connected a pair of audioquest subwoofer cables from the power amp to the subwoofer and it is dead quiet, so through my own personal experience, cables can make a difference! Good luck, Hope you find a solution for your situation.

Well, if the cheater plug failed to relieve the hum, then IMO it is not a ground loop hum

I have a Reference 3 that was dead quiet for a year using RCA and XLR interconnects. All the sudden one day I got a hum which only occurred when using the CDP.
I replaced the power tubes in the Reference 3 and the hum was gone. As an experiment suggested by my dealer I put the original power tubes back in the Reference 3, using the RCA interconnects the hum was back, switched to the XLR interconnect and the system was dead quiet again. The Reference 3 does that sometimes.

We have come one step closer to the solution. The buzz looks like a mismatch between an high ohm pre-amp (like the ARC) and the impendance of the Kronzilla SXi. We found out by using a Kronzilla DM (monoblock) on the right channel and the SXi on the left channel. No buzz on the DM and an audible buzz on the SXI. Solutions are now being prepared. Will be continued!

Broederen

A simple solution that I use in my system when I added the pair of Gotham subs and was thus driving 2 loads in parallel via the Ref 3---thus creating some strain on the Ref 3 was to add the Tube Buffer and its separate Power Supply from Musical fidelity. This is a very simple, effective and inexpensive fix. Musical Fidelity does not make the Tube Buffer any more but if you are interested send me an e-mail and I will tell you of a dealer who has them new and in the box.
The Tube Buffer has an input impedance of 470 KOhms and will solve your problem. If you read the recent posts in my system you will find a description as to how this can be done