sonically they will be similar but i suspect the ref 75 will have more nuance and blackness of background, ultimate treble and bass extension, and potentially, soundstaging
note - i own the ref 75 but have not heard the vt80se in my own setup
paragon av in ann arbor michigan is a major arc dealer, you could call them ask for their advice, i am sure they know each piece very well, they are open and helpful