Home > Consumer Reviews > Pioneer GM6400F 4-Channel Bridgeable Amplifier

After playing my sound system pushing two 12" subs,it got pretty hot but five minutes later it was cool again, loving it so far.

Like the other guys said - it is big, it is heavy. Big and heavy suggests big heatsink, which you want. I haven't opened it up to see how well built it is inside, but the bottom cover is made of that cheap, thin, plated steel that they make generic PC cases out of. In contrast, my 350W Rockford Fosgate sub amp is all cast aluminum and chrome-plated, thick steel. The Pioneer runs a bit hotter than the Rockford amp and the screw terminals are much cheaper than the enclosed terminals of the Rockford, but you gets what you pay for.

I have this amp mounted vertically on stand-offs on the side of my trunk space, with a 120mm PC fan blowing across it. Only gets warm then, even when you start off with the trunk interior at 100°F.

I'm playing a 4-year old Pioneer head unit via the RCA jacks into this amp which drives a pair of [...] 6x8 Pioneer 3-way front speakers and some [...] 6x8 Infinity 2-way speakers in the rear. Sounds nice and clear - no noticeable distortion at a fairly high volume level (that I can't stand to listen to for more than a few minutes at a time). With only the head unit (rated at 4x50W, which is supposedly 4x25W RMS) powering the same speakers, I had to use its built-in HPF to take away the bass below 50Hz, else it would be distortion-a-plenty. Now with this amp hooked up, I can feel the front doors vibrating again and no distortion!

Do yourself a favor - ignore the fairy-tale power rating on your head unit and use a separate 4-channel amp for your main speakers. It just sounds so much clearer and you can enjoy the full amount of bass that your speakers can produce. You don't have to listen at a very loud volume to hear the difference. This is the first time I've bothered getting an amp for the main speakers in a car (and I've been driving since 1988). I've upgraded head units and added small subs, but this has made the most overall difference in sound quality. Next time I change cars, a 4-channel amp is the first thing I'm going to install. Wish I'd figured this out years ago!

Great value.
I had this installed to boost the power to my new Polk Audio front and rear speakers. As far as I can tell it's working according to spec. No problems here.
FYI.. It is a little larger than average.

Great product. Sound is so much better, highs are clearer and lows are deep.

Been in my car for a month or so now and sounds great. I have it hooked up to my 4 factory incar speakers (98 Eclipse Infinity speakers) and they sound crystal clear and very loud. All my settings are set to default out of the box on the amp and the stereo is set for max highs and slightly below higest setting for mids. I dont need to go higher on any of the gain values default is great on the amp. Although Im not using this amp for any bass it sounds great if I do turn the bass level above 0 on my stereo. (I have a seperate amp for bass on a sub)

One thing I didnt like is the way the speaker out part is. They are ontop of each other but the rears extrude out further as if they where steps. It sticks out quite a bit and for some reason left and right are backwards so its right speaker and then left?
Besides that its a great amp, looks nice to with the black and the red on the sides.