Hi @dgozalie, welcome to the Sonos Community!
I’m not as knowledgeable about your type of setup, but from what I could find from our team is that you can send any analog signal but it will be digitized and anything higher than 48kHZ will be downsampled to 48kHZ, so you should be fine to stream your FLAC files at 24/48kHZ.
Regarding the Variable, Fixed and Pass-Through option, these just change how volume is controlled on the Connect, with each meaning:
- Fixed - Your AVR or amplifier will control the volume exclusively. You won’t be able to use the Sonos app to adjust the volume or equalization settings.
- Variable - You can use the Sonos app to adjust the volume.
- Pass-through - Sonos products stay at a fixed volume and will send volume commands to your amplifier. Note: Make sure your amplifier supports Pass-Through. If you set the line-out level to Pass-Through and your amplifier doesn’t support it, you won’t be able to control the volume.
I hope this information helps!
