Hi Peter/All - I just picked up the CQ-20b and love it. Getting started with ST and this mixer. You mentioned in a post you use one. Would you happen to have a quick setup guide to route the tracks from ST to the CQ? And quite possible the setup for CQ, although I think for the mixer it's just assigning the input channels to USB that will play the tracks coming from my ST iPad?
I am a singing drummer and love ST for the lyrics aspect but now ready with the CQ to do backing tracks.
Thanks for your time!

There's not much to it. You can see each channel of the CQ20 in ST3 in Settings > Audio Routing. So assign the tracks to the channels in the CQ20 that you want to use and then make sure that these channels are set to USB input in the CQ20.

I run a CQ18T, and although I haven't yet used ST3 live (still getting sets/songs etc. together) I did test it with my CQ, and it's pretty easy.

USB out of the iPad into the CQ, once that's connected, the CQ is a class compliant audio interface, so inside the ST3 app, you can choose which channels on the CQ you want to output your tracks to. Personally, I run multitrack versions of songs, with a separate click, cues, and various instrument tracks, which I anticipate muting or changing depending on the gig/band in the future.

Ive been using 4 of the CQs channels for this: stereo instrument/tracks all routed to the same channel (even though they are different tracks in the ST3 app), click, and cues routed to two separate mono channels (singer doesn't like as much click in her ears as the rhythm section, so I'll be running those separately.) Click and dues obviously only routed to IEM channels, not the mains.

Worked great in my test!

FYI here's my post/question about in on the A&H forum: https://forums.allen-heath.com/t/usb-interface/16038/9

Also, the CQ operates at 48 or 96k only, so you'll need to set the ST3 app appropriately. (Personally I use 48k for everything; IMO there's no need to kill my processors with the inaudible-in-a-gig-situation extra processing required for the higher sample rates.)