Great, feature-rich amplifier

Because I'm a fan of MTX products I just bought a pair of MTX amplifiers on Ebay, a MXA4004 and MXA6001, which I will review separately.

Starting with the cosmetics, these amps have a really cool flat, dark, "black and chrome" harley davidson kind of look to them. They aren't the usual fin-covered amp, in fact they don't have fins at all. The 4004 and 6001 look identical, and are the same size as each other.

This 4-channel amplifier is rated as 50 watts times 4 at 4 ohms, 100 watts times 4 at 2 ohms, or 200 watts times 2 at 4 ohms bridged. Since this is MTX, you can pretty much assume that under "real world" conditions the amp will put out at least 25% more power than it is rated. Since I bought these used they didn't come with the usual birth certificate so I don't know this amp's actual output.

The MXA4004 has two 30-amp fuses. All of the power and speaker connectors are on one end, and RCA jacks on the other end.

The power and speaker wire connectors are all "compression fit" style, which is awesome! no stupid spade connector screws like on most amps, these make the install really easy, and really clean looking. I just trim the last 1/4" off the wire jacket and screw it down firmly with the set screw, and there are no exposed wire surfaces to short out or come loose anywhere.

The other end of the amp has 4 RCA inputs plus 2 outputs - and all controls. The 2 outputs are "summing" which means if you're running a sub amplifier from them the sub stays at the same volume when you adjust the fader control on your head unit.

The one complaint I have with the controls, is that the switches are TINY and very difficult to adjust. I think this might be on purpose to keep customers from fiddling with them after having the amp installed professionally... but it means you'd better have a jeweler's screwdriver on hand when you install it yourself.

The built in features are: front channels have high pass, low pass, and full range settings on crossover. crossover point is adjustable from about 50hz to 250 hz. slope is 12db/octave. There is a bass boost at 45hz that can be tuned anywhere from 0 to +12db... and of course the normal gain control. Rear channels have the same controls plus an input for a "Remote Level Control" which is a knob you can mount in your dash to adjust the level remotely, like if you're using this amp to power subwoofers. My used Ebay amp did not come with this control, so I don't know how well it works.
There is also a switch for 4-channel or 2-channel input, so that if your radio only has 2 outputs, you can still run all 4 speakers with it. Also there are high level inputs if your stereo does not have RCA outs, like a stock stereo, and according to the manual when you use the high level inputs you don't need to hook up a remote power wire because it senses the audio and turns on by itself.

Enough about features, here's how the thing actually worked:

I "installed" the amp under my seat, because that's the only out-of-the-way place in my car. Power and speaker wires were already there because I previously was using another amplifier, so for me installation took 5 minutes. It looked a lot neater because the compression terminals on this amp make the wires look much tidier, and its smooth black exterior make it look less like there's an amplifier under the seat if you happen to see it while sitting in the back seat. Setting the crossovers was easy after I found a little bitty screwdriver to move the switches with, and used the same screwdriver to turn the adjustment knobs. There was plenty of gain range to accept the 2v preamp output level of my head unit, i would imagine if you have a nice head unit with 6+ volts preamp output it would still be well within the amp's range, as would a 1.5v pre-out (like some really cheap decks have) . I did not hook up the high level inputs as there is no reason to in my install.

The amp is presently powering some 6.5" components in the front and a 10" MTX 5500 subwoofer in the rear, until I can afford some new rear speakers.

It gets kind-of warm when I listen at relatively loud volumes for a while, like uncomfortable to hold your hand against it for a long time - but not "too hot to touch"... it hasn't shut down yet even when I play it very loud on a long drive to Tucson. Powering a single 10" subwoofer in a vented Sledgehammer box off the rear channels is enough bass to make my hair vibrate and the mirrors on my car useless, so it's plenty for my listening tastes. The music I listen to is mostly industrial rock and hip-hop.

I guess that's about it. Like every MTX product I've bought so far it does not disappoint. I'm looking forward to hooking up the MXA6001 later and reviewing it, too.