some help getting started with multi-channel USB audio

Hi,

I have a 15-year-old computer newly installed with FreeBSD 14.1, plus a 2nd gen Focusrite Scarlett 6i6, and a Novation Launchpad Mini. 

The Scarlett 6i6 is an older interface with 4 A/Ds and 4 D/As, plus 2 digital pass-through channels.  The Launchpad is just a MIDI controller with some lights and some buttons. My intent is to set this up without any monitor or keyboard, and then use the buttons on the Launchpad to control recording and playback from the various channels on the Scarlett.

Here's where I'm looking for help: what can I do to get independent access to the six channels on the interface?  Is there maybe some combination of sndio / oss / alsa / jack that will nicely present each channel as a device? 

Thanks,

JD