I could tell you to just go listen to em, but that wouldnt be helping you much..
If you have access to a good set of speakers (home enetertainment/ pc / whatever..), try this..
take any audio material (song!), and insert some square waves in the 50-75 hz zone (depending on the slope your software can do). Now the amount of noise you inject should be proportional to the difference represented by the THD in amp A vs the THD in amp B.
I'm not saying you wont hear the difference, but its very very unlikely. Some people live for SQ and can probably hear more detail than most
..
This thread is a little goofy.. You're probably expecting serious answers, but you havent given us all the details..
-price range
-type of music
-enclosure for subs
-type of listener you are
-what do you expect from this amp..
The 10.1 Kappa is a pretty good sub! I love the 12.1.. But if you are serious about SQ, then this is only mid level stuff.. Its the mainstream SQ sub.. So suggesting an amp made for all out SQ wouldnt really make sense..