I have heard both KH150 & KH310 in different settings. I auditioned the KH150 and really liked it, then went ahead to buy the KH310 which is now at home. I find the two speakers very similar yet slightly different.
This is my subjective opinion on the differences:
- KH150 imaging is pin sharp, the KH310 is just slightly less sharp than the 150.
- KH310 midrange sounds really good and natural especially for female vocals.
Tonally, they are both very very similar.
Just thought I should put my subjective opinion out there...if it helps...