interpretation of dealer speaker statement needed


Please tell me what this means in English; in advertising a pair of speakers for sale, the dealer said:

 "This speaker does have a combination of somewhat difficult impedance and negative phase angle in the upper bass, just like most loudspeakers of this type and size.  These are not a good match for SET-class amplifiers."

These are not oddball speakers but a very respected manufacturer.  They are a 3 way bass reflex,
 with (2) 6" woofers, a 6" mid-range, and a 1.1" silk dome tweeter. 

What is the dealer trying to convey?
rockeymarkb

Showing 1 response by gbryant