Feature request: mux/compile multiple destination files into one

[MrSimmo]

It would be great to be able to have the option to mux / compile / merge the destination files into a single file.

So for example, bring source files:

1_filename_(bass).flac
1_filename_(drums).flac

into:
1_filename_(remuxedoutput).flac

Ffmpeg could be used to do this; a command something similar to:
ffmpeg "${wav_files[@]}" -compression_level 8 -filter_complex "amerge=inputs=$(ls *.wav | wc -l)" -ac 2 "[output.flac]"; then