I switched to the official Java 8 runtime, and that solved *half* the problem. I now didn't need to put any stupid extra parameters in - it just found the Pulseaudio system and send audio to all outputs.
However I hit a NEW problem. For some reason, the outputs are always Muted, and I have to unmute every time I start playing.
(alsamixer, then scroll over to the output and hit M)
Disabling "auto-mute" didn't fix it in ALSA so.. i don't know.
Give MPD a try instead of Subsonic?