If i have a midi track routed to a vsti then what is the benefit or what effects processing can I do on an audio file that I couldn't do otherwise.

2 choices...

download the newest version of massive.... which doesn't crash!! AT ALL!!

create a new audio track, insert a test oscillator & then a gate. side chain the gate to the bass channel,
tune ya sine to suit (oscillator). ya can automate the freq too.

look online for note freqs to keep ...

Booyah