I haven't had any experience with the SX's but I can vouch for the KX's. AMAZING amps IMO, I had a KX600.1 running at 1 ohm for like 6 months (It's only supposed to be 2 ohm stable). And the friggin thing hardly ever even got hot! Kicker makes great amps, wish I could afford a 2500 for my XXX //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif