We put in Mary Chapin Carpenter's Come on, Come on to see how the Kicker would handle female vocals. Her voice was well centered even through some of the over-processed tracks. There is a song called "Only a Dream" that features a well-recorded piano. The low-end and mid-range sounded solid, almost too solid. The highs seemed a little indistinct on this track as well. Not like it's been equalized, but just not quite there.
During this phase of the listening we noticed a clicking sound when adjusting the volume at low levels. Imagine a slow "zipper" sound in which you can hear the individual teeth of the zipper, which stops when you stop turning the volume knob-strange, but low enough to not be terribly annoying.
We played around with the Kompressor(tm) a little, but it seems to be geared more to the subwoofer side of life. No problem, we quickly rewired the Kicker on a 12-inch dual voice coil in a sealed box, reconnected the separates and grabbed an old CD sampler from some car audio show. (We honestly don't remember what it is, but we think we picked it up at an event in Idaho years ago. There's a kid named Billy and his deaf Grandma yakking between tracks of sine bombs, sweeps and various bump tracks.) The Kicker and the 12-inch made for a fun combination with no lack of bottom end. The amp was able to reproduce the lowest of the sine sweep frequencies easily, and the Kompressor(tm) worked wonders. In a nutshell, a compressor decreases (compresses) the dynamic range. It makes the difference between the softest and loudest signals smaller. This means you can hear more of the softer stuff in between the loud stuff. Trust me, it's a good thing.
ConclusionOverall we thought the SX400.2 performed well. It has a lot of digital stuff and operates glitch-free. The DSP functions are accurate and clean, and the Kicker engineers have solved a lot of I/O problems that other companies are still wrestling with. The interface and menus are well thought out and easy to navigate. The amp lacks sizzle in the highs, but low-end and mid-range are as solid as they come. The retail price on the SX400.2 is $599.95, and at a maximum power of 425 watts, you're paying $1.41 per watt-definitely on the high side for this power range. On the other hand, you're getting the most-impressive crossover available in car audio, a single band parametric equalizer and selectable compression, plus a few goodies that are just fun. We're not sure what that's worth in car audio (check out some pro gear catalogs), but it seems like a good deal to us.