I bought a pair of Kappa 8.1's from the original owner's son a couple of summers ago and loved them so when a pair of Kappa 8's popped up not long after, also from the original owner, and with their boxes, I went and brought them home and they are now playing right in front of me while I type this..I do think the 8's have a little better sound quality than the 8.1's but not by much..The bass is definitely a lot tighter on the 8's since they aren't ported and the highs more defined..I have a Onkyo M504 pushing them but just replaced the P304 pre amp 2 days ago with a Acurus L10 which has dual outputs so as soon as I pull my B&K ST 202 out of the closet I will have it pushing the bottoms and the M504 on the tops..Btw, the Acurus L10 blew away the P304 in sound quality