I’m running Paid for Ardour 6, AV Linux 64 bit, native 7.1 Soundblaster and 2 interfaces:
Presonus Audiobox 2x2
Zoom H2N usb mic (can record my guitar and/or voice either on sd card, or directly via usb. Also has an available line out.
Each interface works beautifully on their own. My question is can I set up Jack so on one Ardour session, am I able to switch one interface on, then later switch to a different on?
Using ALSA or JACK you can certainly stop the audio system via Ardour’s Audio/MIDI setup dialog. You can select a different audio device then immediately restart the audio system (maintaining same sample rate would be a good idea).