I haven't used the AXE I/O put I have used several of IK Multimedia's other interfaces and they work/sound good. Great value for their price points. I have the iRig Pro as a travel interface you can hook up to a laptop or phone/tablet that might work for you and sounds excellent.Anybody have experience with the Axe IO?
Also something like the Line6 HX Stomp can be an audio interface or work stand alone, might be overkill feature and price wise if you're not interested in the FX and amp/cab modeling. It does sound excellent for bass my fav headphone practice solution.
Lastly there are several small mixers that double as audio interfaces so you could look at that, they've obviously work the same as when not connected to a computer and then serve as the audio interface when needed. So that might be an option worth looking at.