[LAU] Building an Open Source keyboard rig

I've been considering upgrading part of my keyboard rig by getting a Nord Stage 2 EX. I figure it would give me a much better piano sound than my aging Yamaha P90, authentic mellotron (very important), and some back compatibility for the synth section of my old Nord Stage Compact. But it's £2500. £2500 could buy an awful lot of Stuff. So I started thinking, what could you build that would be Open Source and broadly equivalent to a Nord? Extra points for surviving unexpected power outages and booting fast (damn those dodgy festival power supplies) and for being the sort of thing that you can operate easily having left all your geek credentials in the bowl of brown M&Ms. I figure some sort of Mini/Nano ATX with SSD, stripped back systemd boot, Jack, LinuxSampler, a reasonable low-latency multiple output soundcard... some leftoevers for good quality sample libraries... Let your imagination run wild... how would *you* build a Tux Stage 2 EX? bjb