Just experienced problem with my 5 week old 700rb115 combo. Plugged it in powered up no problem but 3 or 4 mins later after a puff of smoke it returned from green to red power LED and nothing but loud hum! Nothing was connected to the combo when this happened and it was perfectly dry and climatised when powered up. It's on the way back to the UK distributors for inspection and hopefully replacement and I've been loaned a smaller GK combo. I'm certainly not put off by this as I just love this combo but I'm hoping this is resolved quickly. Has anyone had the same experience or suggestions what could have happened?