Axiom Home Page Forums General Discussion Advice from Axiom Owners LF "burps" from my EP500

My EP500 makes frequent LF "burping noise" that has only been noticable in the last couple of weeks.

At first I thought it was interferance from my HTPC directly behind it or from the amp but these "burps" happen when everthing is off except the EP500 which I leave on. The sound is low volume and low freq so you only hear it when on pause or mute or the equipment is off.

Any idea what is causing it and any solutions (note: I do not have a filtered power supply feeding my AV equipment so I could try this)

Thanks
Nathan