Output levels incorporating outboard gear with Ableton

I’m using Ableton Live with some hardware 1176’s, La3a’s, and API 525’s. I’m having trouble knowing the optimum level to send individual tracks to these units. When the peaks are are averaging -6Db, the units input has to be cranked all the way to BARELY receive any compression. I end up using a utility plug in with tons of gain to get the compressors to respond, but the faders in Ableton are way into the red. Is this the only way to do it? Help please! Thanks!!

I’m using Antelope 32+ converter..