Amplify MIDI?
 

I understand that a MIDI controller CAN NOT PRODUCE AUDIO, just sends signals to the computer and back. From the MIDI controller, I run a USB--> computer--> Presonus Software--> Sound from computer speakers.

I have:
M-Audio Keystation 49e (via USB powered)
Casio WK-220 (DC 9V battery powered)
Presonus Studio One interface
Roland 8 track mixer w/ L/R speakers
Cube 30 Bass Amplifier

I get sound from plugging my MIDI straight into the computer, and through the computer speakers. Problem is, I need the MIDI sound from the computer to run through my PA speakers or bass amp.

QUESTION: How, or can I get my MIDI's AUDIO--> from my computer, run the sound from the computer--> to a mixer/bass amp???

GOAL: Amplify MIDI sounds from my computer, through my PA speakers or a bass amp.