Yes, Bryan, Albert runs Soundlabs, so the "woofers" weren't pumping, but he had a feedback like sound coming out. It was frustrating, but he eventually found that there was something causing the IO to vibrate and cause this problem. In his case it wasn't subsonic, and maybe the excitation in your case is at a different frequency, but it might be solved in a similar way. With the amount of gain at micro signal levels in that IO, it doesn't take much to make something happen.
As far as your woofer pumping goes, it must be a signal or resonance of some kind. I'm sure the IO must have a relatively low output impedance of around 1k Ohm or maybe less. That should be just fine with the Lamms. Did you try running it with the tonearm leads unplugged? That would isolate the problem to either the IO or the turntable. I just have this gut feeling that it's not an impedance thing when going direct from the IO.
Glad I'm not butting in. :^)
As far as your woofer pumping goes, it must be a signal or resonance of some kind. I'm sure the IO must have a relatively low output impedance of around 1k Ohm or maybe less. That should be just fine with the Lamms. Did you try running it with the tonearm leads unplugged? That would isolate the problem to either the IO or the turntable. I just have this gut feeling that it's not an impedance thing when going direct from the IO.
Glad I'm not butting in. :^)