After the second time sending my then new A250 back to Mondial to fix the same annoying buzz, I sold it. Note the buzz had been fixed again, I told the guy who bought it all about it, and have no clue if that pesky buzz reappeared...Mondial may have fixed it for him too! Note it sounded excellent when working properly, and I auditioned one of their preamps and that was great sounding, but by then I was a little too worried about the reliability.