I recently bought a trumix usb interface (PMT guitar shop branded device from UK) in the hope I could connect to Jammer through my mac mini. Although other Jammr players can hear me, I am told that the signal is too quiet. Its a two channel device and I have tried going through both via a Boss Katana amp. Does anyone have any advice on how to connect with decent levels?

I would be happy to get another usb interface on a recommendation that it would work.

Thanks in advance for help and advice : )

Here are steps you can try to get the best signal and volume level:
1. If you are plugging your guitar directly into the interface, set the input to INST. Otherwise set it to LINE.
2. Play your instrument as loud as you would play and make sure the the SIG (signal) light is on but the CLIP (clip) light is mostly off. Adjust the gain knob if necessary.

Now you have the loudest (clean) signal set up. You can turn the gain knob down if you find it's too loud.

In jammr, go to the sound settings and tick only one checkbox in the channels list. That way jammr will treat your input as a mono signal, preserving its volume level.

Hope this helps!