Live audio input via Alsa?

Hi there

I would like to turn my Volumio Pi (v1.4) rig into a pre-amplifier/controller for my hifi system, so we have the option to play digital audio straight into the power-amp, and bring analogue sources in through MPD. This seems barmy, but with vinyl and video being the other sources, they’re compromised enough already that digitising into our chosen usb interface isn’t a significant enough problem to be worth worrying about.

My theory is that 24-bit software volume control is likely of higher quality than the present analogue pre-amp section, and gets rid of the volume imbalance issue between left and right channels at extremely low levels required for night-time listening in London flat.

I’ve tried adding the Alsa input plugin to MPD.conf manually, and issuing the “mpc add alsa://” command to mpd after a restart, but it comes back with an error about an unsupported URI. My best guess is that MPD for Volumio has been compiled without the ALSA input plugin option - is that right? If so, is it something that could be done in another way without a recompile?