native plugin instrents, plugin formats, audio mixer

Multi Instruments
https://www.youtube.com/watch?v=YA-ODMD19as&feature=youtu.be&t=3m50s
vst3 plugin support
http://www.steinberg.net/en/company/technologies/vst3.html
lv2plugin support
http://lv2plug.in/
Kontakt or Presence XT like built in Instrument
https://www.youtube.com/watch?v=VdlQqQT8ZW8
https://www.youtube.com/watch?v=ILY1sNggnjw
simple Multi sampler like Studio One: Sample One
https://www.youtube.com/watch?v=5AajElAf4S8
https://www.youtube.com/watch?v=PyKVtYGusxo
ladspa plug ins support
http://linux-sound.org/ladspa.html
audio
https://gstreamer.freedesktop.org/
helm built in
http://tytel.org/helm/
hardware like mixer
https://www.youtube.com/watch?v=wn1SvzR2Nv4
folder track
https://www.youtube.com/watch?v=hMzJ0Wd6ygc
Basic Editing
https://www.youtube.com/watch?v=bXLtAYwH7XM
sorry about the list but I am a programmer anything I can do to help