IdPi is a custom Raspbian distro with JRiver Media Center pre-installed (and pre-activated) that runs on a Raspberry Pi.
The IdPi SD card is just a SD card with the custom IdPi distro with MC pre-installed that you plug into a normal Raspberry Pi you're already running. It won't work for the newly released Raspberry Pi 4 Model B yet. Bob's working on an update for that.
The fully baked IdPi is a pre-assembled Raspberry Pi 3 Model B+ in a case with the SD card with the IdPi distro installed. I wouldn't be surprised if the Raspberry Pi 3 Model B+ IdPi model is replaced with a Raspberry Pi 4 Model B model real soon.
It doesn't have any inputs other than what a Raspberry Pi includes (so 3.5mm audio jack and HDMI) but the onboard audio on a Raspberry Pi isn't that great. You'd have to either add a USB DAC to it or add something like a HiFiBerry board to it (which you'd probably have to get a new case if going this direction as it won't fit in the official case with a HiFiBerry board added). If you're wanting digital output (e.g. S/PDIF optical/toslink) you'll probably be looking at the HiFiBerry Digi+ if looking at the HiFiBerry route. However, I don't think Spotify, Tidal, etc. will work unless there's native ARM Linux apps for those that run on Raspbian (and MC itself doesn't support those). If there isn't Spotify, Tidal, etc. apps for ARM Linux (Raspberry Pi/Raspbian) then there likely isn't a way to do it there.
