https://hackaday.io/project/178760-3d-audio-producer may be someone will like to play with it (it does not make giant 55 channel audio files, instead it tries to play many-many mono sounds in 3d space for stereo sound systems (or may be 5.1 ones)). Even if it does not have render to file features (?) you probably can capture it via alsa/pulseaudio loopback ?