SET amp w/Neg feedback?

Jtgofish, that is not entirely true, although there is a class of loudspeakers for which it probably is. see:

http://www.atma-sphere.com/papers/paradigm_paper2.html

for more information.

Negative feedback violates one of the more important rules of human hearing by enhancing the odd-ordered harmonics used by the human ear as loudness cues. Hundredths of a percent is quite audible- bright, hard, harsh, clinical, chalky... -these are all words to describe extremely slight amounts of odd-ordered harmonic distortion.

Atmashere,
I am sure what you say is theoretically correct.
I have had the opportunity to use amplifiers with variable feedback.Experimenting with the amount of feedback is very interesting.Certainly too much detracts from the sound.Most noticeable is the collapse in depth and precision of soundstage when too much is applied.
However to my ears a small amount of feedback gave a much more controlled and natural sound than no feedback.
P.R.A.T. was much better.

Jtgofish, if you have a speaker designed using Voltage Paradigm rules, then what you experienced is absolutely right. We have had similar experiences.

A speaker using Power Paradigm rules will often work better, including the bass, using an amplifier without any feedback at all. Obviously such a speaker is designed expecting a different set of rules from the amplifier.

Atma - how do I know if my speakers are designed with voltage or power paradigm? (EgglestonWorks Fontaines)

Rockadanny, it all has to do with the intention of the designer. In general, if the designer uses tubes its probably a Power Paradigm speaker he created. Voltage Paradigm designers usually use transistors. That will answer the question about 95% of the time. Beyond that, its a good idea to talk to the designer and/or read any white papers he may have written, or simply ask what sort of amplifier he recommends.

The equipment matching conversation that is all over high end audio is a direct result of the conflict of these two paradigms.