Qjackctl is a graphical jackd management tool and allows easy routing of jack aware audio connections.
root # emerge qjackctl
add users to the realtime group:
root # gpasswd -a $USER realtime
Qjackctl can be tricky to setup. select settings, set realtime to give the program direct access to your sound device.
Sometimes with multi sound card you must manually set the interface to your preferred device. (if at this point you cant get qjackctl to start reliably, try disabling realtime)
Buffers should be as small as possible with out xruns. maudio mobilepre usb example: Frames/Period 256 & Periods/Buffer: 2 results in 23.2 msec latency which is pretty good for a usb 2.0 sound board. Loading some programs can lag the system resulting in an xrun, but that's ok so long as it's not constantly xrunning. make sure that your system doesn't flood with xruns for the program combination you will be running, it will probably require more buffer than just Qjackctl alone running.
start delay, having a slight delay prevents xruns from the jack server starting up.
The connect button brings up a dialog window showing graphical connections of programs and hardware devices. it is possible to connect system in to system out for direct guitar 2 speaker connections.