Get yourself a dedicated desktop (not a laptop)
I use adobe audition 1.5 – 3.0 is ok, never warmed up to sonar or pro tools, it’s up to you. I only use audio so 128 tracks is good.
Add an audio card, I recommend, RHE sound card,
Get a mixer – I have a Heath and Allen mixer
Run your keyboard to the mixer, then to the audio card and run the outs to your speakers.
To listen to the results I get you can listen here.
http://chipos.com
Let me know if you have questions are even want to go this route.
I have messed with every USB sound device (Motu, Mbox, ect..) and nothing beats a rig…

Good luck
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I don't steer the ship... I bail out the water...