Have updated my music player to use the JACK low-latency realtime library for output, and replaced Mplayer with alsaplayer as the media player. Have also dropped the Meridian 518 and Yamaha decoder from the output chain, feeding audio straight into my Bryston via the music box’s onboard DACs.
Given the hardware (and purpose of the box), there’s little benefit to be had from the low-latency features of JACK, but the realtime support helps keep the output smooth in the face of other stuff running on the box (CD ripping, for example).
And something in the combination of the simplified signal path and JACK/alsaplayer has definitely tightened up the high end a bit more, which is always a good thing. If only I had some Vivids to audition this all properly!
Now what I really want to play with is to tweak JACK to emulate the 518’s noise shaping/upsampling algorithms. Later…