old Cadence amps were supposed to be a good bang for your buck. Don't know much about the Aussie company now-a-days though. Their speakers/subs look kinda cheap and shitty. IMO
The ZRS-9 is a great amp. It has a better S/N ratio, so it'll be slightly better in sound. They're both great amps, but I'd say the Cadence is slightly better because of the S/N ratio, and the price tag (not much of a difference though.)
i like cadence too. i just picked up a z1500 a few weeks ago but i need to sell it and get a hifonics or something else that is 1 ohm stable. the z1500 does 1500 at 2 ohm. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif