DHE is a DSP. Each of the 5 modes do different things to the sound. Older rock recordings that really lack any bass really sound much better when I use Bass Mode 2 and it 'fills' in the sound. For most other recordings, I use Vocal Mode because it cleans up the sound really well and gives that bass a harder hitting and crisp punch. Midbass also becomes more defined. Audio books sound really good - I use those two modes the most. FM radio always sounds like it's missing something and so I find that All Mode works really well with sound through radio broadcast. Its hard to describe and needs to be heard to be fully understood. On top of these modes, the 7-band eq can be adjusted to tweak sound a little further. Bass Mode 3 is the only one that really sucks. Bass Mode 1 helps make jazzy sorta beats come to life too.

Digital time correction is a delay adjustment so each speakers' sound reaches you at the same time.

Black out display means the display window shuts off whenever your not pressing a button. It does not clash with the empegs' display at night. The alpine just looks like it's not on except for the illuminated buttons.

Customized sound database finds out if your car has cloth or leather seats, what size tweeters you're using, if your car is a hatchback, sedan, convertible, etc., and makes adjustments to optimize the sound output.

You know what a cross-over is.

Subwoofer level control is a quick way to lower or raise the thump from your subs. Some songs have more bass than others.

The CD transport (3 lasers AFAIK) things is unique to only 2 alpine models. It allows instant playback of mp3s. When a mp3 CD is inserted, it takes a whole 3 seconds to read the disc and after that switching songs/playback is instantaneous. Other HU's take a (long) while to read the disc after insertion and take forever to switch to the next song. Since I have an empeg, this isn't really a big deal anymore but when I didn't, it made a world of difference. Just the sound quality this unit produces is top notch. I'm convinced it'll be an alpine classic like the 7909 of way-back-when and I won't ever sell it.

Oh yeah, I can crank this sucker (as much as I can tolerate) loud and it does not clip or distort the sound. Anyone who listens to it really lets me know that they think my system sounds sweet. It's not IASCA material but I like it very much.