my amp goes silent on record or monitor mic

Recording works but I can’t hear my amp when I record or when I click on mic monitor, so therefore I can’t hear any effects - just my guitar without amp. When I stop recording - the amp works.
One work around may be to enable playback while I record but then I’d have to mess with latency.
I’m using the usb connection from amp to computer and my guitar is connected to amp with standard cable. I’ve tried this on my PC with openSuse 13.1, another PC with Windows 7 and my notebook with Ubuntu 14.2 with same results.
I don’t see anyone else with this problem when searching online.
Any suggestions would be appreciated.

So is it some kind of USB effects amplifier? Please give the make and model number of this USB device.