Playing Live Sound from PC - Need Help

I’ve been struggling trying to get my studio hardware setup just right. The intent is to play live sound, piano instrument only. Wanting to simulate 9 unique outputs. Cubase 8 works great. No problems at all. I have an RME hdsp9632 and using ADAT into an ADAT converter. From there into an amplifier. Everything is using shielded XLR cables.

My problem is I get distortion out of the speakers. I’ve tried different amps, adat converters. I’ve tried using the analog only of the RME into an amp. The analog is clean, no noise at all from the RME analog outputs. I’ve tried everything except for changing out the RME board.

My question is, what is the best PC configuration if I want live sound and not for recording? I’ve always thought the issue was downstream from the RME.

Goal is to get clean sound same as headphones.