My list of what to look for in a audio interface.
Good Mike Pre amps ( unless you own a dedicated pre)
As many inputs as you would use ( in your case 1 or 2 )
Seperate controls for both Monitors and Headphones-on the front.
A mix control to blend input and output to monitors and phones.
SPDIF input if you do purchase a mike Pre amp or own a digital mixer.
MIDI in unless your controller is USB.
MIDI output if your using outboard old school synths and drum machines.
AND most important- GOOD AUDIO DRIVERS for your operating system.
Low round trip latency if your using real time EFX. Not a problem if your not a guitar player , really.