Negative Feedback a deal killer?

If you can audition it, that should settle the case for you.

It all depends whether you like distortion. Appropriate use of negative feedback has been conclusively & scientifically proven to reduce distortion. Therefore, if you like distortion then you will not like negative feedback.

Audiophiles are often fond of attributing all sonic traits of a component to a single issue. It's rather analogous to a car buff assigning everything about an engine's performance to cubic inches.

It is almost never that simple for either audio components or cars. Negative feed back is just like anything else. It can help or it can hurt. It depends on implementation and how it is integrated with all other technical aspects of a design.

That said, I don't know anything about Unison amps, so take a listen if you're truly interested.

From what I gather it depends a whole lot on what speakers you're gonna use with the amp.
That, and if you like distortion :)

I always loved the look of those Unison amps.