My O/96's sounded ok but not quite "right" when paired with a Pass
XA30.8. However when I moved to a Line Magnetic 805ia 48W SET they
simply came alive, especially when set a no negative feedback
As is stated in the article I linked from our website, any time the two technologies are mixed (power paradigm amp with a voltage paradigm speaker or vice versa) you are likely to get a tonal aberration. This is because the two camps take a different means to neutrality.
The voltage camp is based entirely on the idea of flat frequency response, the power camp is based on the idea that the distortion caused by the use of feedback (which is all higher ordered harmonics and IMD) is going to be more audible as brightness and harshness. No speaker is going to be flat regardless of the amplifier used. So keeping the distortion inaudible is regarded as more important.
The thing is, the output impedance of the amp affects where the crossover points are as well. For example if the output impedance of the amp is low, a choke in series with the woofer will cause the highs to roll out. But if the amplifier impedance is high, the roll out frequency will be moved up significantly, possibly a couple of octaves!
This is why many loudspeakers meant for amps with a high output impedance will have level controls for the mids and highs, since the voltage response of the amp is an unknown. Those controls are there to set the speaker to flat (and not to tune it to the room, like I used to think when I was a kid).