Here's a test for you.

You get random static in playback. So.... render the song to a WAVE and see if the static is in the song or not.

If the static isn't in the song, it's a buffer still not set right. Static and crackling comes from the buffer not being able to keep up with the real time action. Usually when you're running a synth from midi. It's rare to get static from audio tracks.

My guess is it's not hardware or cable related. It's in the software, driver, buffers, latency settings. Dig deeper.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.