Hi. I can't be sure that your keyboard is properly working through the adaptor.
I feel those lines encouraging.
IO hw:3,0,0 USB2.0-MIDI MIDI 1
O hw:3,0,1 USB2.0-MIDI MIDI 2
Even if I reccomend open sorce software, I want to link to you some commercial one for linux. They are not free, but have useful free demos: http://www.pianoteq.com/ (actually my favourite phisically modelled piano) http://www.renoise.com/ (just tried it). Those programs should work without jack (I'm sure that pianoteq works without jack). Have a try by downloading a free demo from pianteq site, unpacking it and runing it. Try to play around with audio settings until you can hear and play. If you can't, we'll know that keyboard is not working properly. Does your Audigy MPU-401 have a MIDI port?