VPI SDS producing hum at 45rpm

I've never had any luck getting ahold of them, actually. Their phone system doesn't allow for messages and they've never picked up the times I've tried.

This morning I'm noticing the hum at 33 rpm too. I wonder if the exposed design of the XV-1s is more susceptible to interference from the VPS. I can't easily move my VPS so I'd like to get a good feeling that that is the problem before I go through the hassle.

I did have a hum problem even without the SDS, but it was a different problem (and the solution was crazy), but I have more info on the SDS.

If I run the SDS at 33 and change the belt to 45, it runs fine. With the belt at 33 and using the SDS at 45 rpm, I can hear the same frequency of the hum emanating from the TT (arm still on arm rest). When I touch the arm (e.g. to move it) it is vibrating. Not visibly but it feels like you're holding an electric razor. Also, when starting up the TT at the 45 setting on the VPS, the table shakes violently (on top of my Cloud 9).

So my problem was that my table, while nicely isolated from the shelf (via my Cloud 9), wasn't perfectly isolated from the motor. A simple shift solved the issue.