I found this alsa_in command a long while back, and modified it for My Fender Mustang usb guitar amp.
/usr/bin/alsa_in -j mustang -d hw:0,0 "Amplifier.0" -q 1 2>&1 1> /dev/null
and it's still useful letting me have my midi keyboard and usb guitar amp as separate input devices for simultaneous
use in Reaper, in this case. So when a musician friend stops by, and you want to record a duo,
it's pretty easy hook up your gear, launch qjackctl, note the gear titles, and change the command a bit, as needed.
Or if alone, and you have synths with a latch-mode, or a sequencer or a drum-machine running, they can play on the midi side,
while jamming the guitar part in an audio track. A nice practice/recording scenario. Several brands of older usb guitar amps
may also work, in the $50-$250 price range. Line6, Peavey, Boss, Yamaha etc. Sounds can further be modded by rakarrack
or guitarix or calf etc