With the SQ, you can send multitracks over the USB port to your computer. This is a very latent connection (ie it is very slow), but doesn’t require any additional hardware to make work. You simply need to route the audio out of the SQ’s USB port and into the Waves Performer software. That means checking the routing page for each device/software and ensuring it is set up correctly.
The Avantis does not send multitrack’s out over the USB port. Therefore you must have a I/O card (Dante, Waves, or Madi) that can send/receive the audio from an attached device. If you use a Waves card, then I would suggest that you skip the “Performer” SuperRack version completely and use an actual Soundgrid Server with the regular Superrack software to ensure the fastest latency times (sub 1ms roundtrip). You can DIY your own SoundGrid Server if you desire to, but it still requires a valid Superrack license as well as valid plugins.
The next most common option is to use a Dante card for this transfer of audio. You will need to connect your computer to the Dante network as well. This requires that you use one of two methods: The Dante Virtual Soundcard software from Audinate or a hardware Dante solution (PCIe card or USB interface). The DVS option is the cheapest, but it also has very slow latency times. The hardware options are quite a bit more expensive, but lower the latency times dramatically.
Once you have your signal chain figured out, you still need to properly route the audio in the Avantis, the Dante Controller software, and whatever application you are using on the host computer (Waves Performer in this example) to ensure the audio gets to and from the console correctly.
PS – theoretically you can use tielines to send audio from the Avantis to the SQ to be send out the USB port to the computer to be processed, and then back to the Avantis to be used there. However the act of transferring the audio to/from the SQ is going to add even more latency to the signal chain.