by Electrodynamic

Pros: Sound, power, crossover flexibility, easy power connections
Cons: Physical size

The 100.4 from Sundown Audio is an incredibly good performing amplifier if you're looking a 2 channel, 3 channel, or 4 channel amplifier.

The first thing that I noticed was the look of the amplifier. The satin black amp with a polished center piece looks really classy. Power connections are equipped with phillips-head screw drive, which means you don't have to fumble around with allen wrenches to hook up the power connections or the speaker connections. A single phillips head screw driver is all you need.

Flexibility oozes from the amplifier. Not only are the crossover slopes steep, but the neat thing about the "rear" channels of the amplifier is that they can be high-passed (mids/highs), low-passed (sub duty), or band-passed (midbass only).

The midbass is very very tight, punchy and controlled with this amplifier. I swapped out a Hifonics XX Olympus for this smaller 100.4 and even though the Olympus is supposed to have 250 watts x channel whereas the 100.4 is rated at 100 watts per channel, the Sundown 100.4 kicked the HIfonics XX amp to the curb in accuracy, detail, and control. And it did it without a significant loss in output. The neat thing I noticed was how much cleaner the 100.4 sounded overall. The XX might have had more power by the numbers, but the 100.4 was definitely more listenable even at higher volumes.

The top end is smooth and detailed, unlike the XX amplifier that was harsh by comparisson. Midrange is more natural and non-fatiguing than my comparisson amp too.

After 2 days of listening to the SAX 100.4 I sold my Hifonics XX Olympus. The "little" 100.4 packed more punch and better fidelity than the XX Olympus did.

IMO there isn't a better 4 channel amplifier in the car audio market today. Sure there are amps that are smaller, bigger, flashier, but the 100.4 has enough features to satisfy anyone.