Wesley,
Thanks for the answer it was very helpful. It helped isolate where the problem lies, which is the interface between the StudioLive 24R (rack mixer) and the Studio One 5 software. I followed the YouTube channel and could only reach a max volume of -24 for my external bass and external guitar plugged in with a 1/4" cable (no mic). This was with the instrument volumes and all gains maxed out. It's loud in my headphones (disconnected them and looked at signals only) but the input into SO-5P is just too weak.
Is there an interface software that I didn't download but should have? Or a button that needs to be pushed somewhere?