Reference-3004A Reference Series 4-Channel, 75w X 4 Amplifier

So I bought this to add to an aftermarket head unit that just wouldn't produce the sound I wanted. Glad I did. Fit and finish is awesome, and connections are straightforward. Instructions are written for those who already have an understanding of amps, but I don't hold it against because anyone can research necessary info, as I have done. You will need an amp wiring kit (8 ga. okay, I used 4 ga. for batt and ground) with 4X RCA cable connection, and you should use Speed Wire cable for simplicity. Edit 9/8/25: Amp still sounds fantastic through my little Polk 75W speakers. This is a great amp for those who want great sound and don't want to break the windows out of your car/truck. For those interested, use RUSH 2112 as a starting point. You will hear things you have never heard before. I'm thinking of putting the Infinity sticker next to Sabian and Pearl on my vehicle, I am that impressed. (I'll use this word again) "Fantastic" sound. Clear, not kidding. If you are on the fence, buy this unit. It takes a bit of work, but it will be worth it in the end; you will not be disappointed. Hope this helps some. First time listening through this amp out of the box was fantastic, with clear treble and bass. So I dialed up a notch and decided to follow Crutchfield and others' advice to adjust gain according to the input from head unit. What I found using multi-meter was that the more I adjusted gain, the larger the voltage disparity between outputs, even from left to right front, and L to R rear. My Polk DB572 Speakers are 75W RMS, matching the amp, so SQ. RT of 75x4 = 17.32v per channel (speaker). The recommendation is to adjust gain at 3/4 output (for me, 30). This did not work well for me; voltage readings were all over the place, it sounded terrible, and I was getting feedback through speakers while accelerating, though I used a solid 4 ga. ground to a great connection. I tried everything to make this sound better with gain adjustments, then I decided to just turn the gains back down to 0. Sounds awesome again, and I have been hearing things like bass licks in music I had NEVER heard before, at even less than 3/4 output from head unit (<30 volume). To be fair, it probably has something to do with my cheap head unit, so your results may be better. Bottom line, this amp is fantastic out of the box, great looking and even better sounding. Very happy so far. Be wary of the gain/crossover adjusts. I set Crossovers to 3/4 and everything sounds great. Gains I left at zero. I used a paint marker to mark switch adjustments so that I knew where they were (no indicators); I recommend anyone adjusting to do the same. Another suggestion to those trying this amp: not sure of the cooling of this since heat sink is barely discernible from the rest of the case. I positioned mine so there is plenty of airflow under and behind. Harman recommends you position the heat sink (side opposite connections) upward for heat dissipation for vertical installation; mine is installed horizontally with much space around. So far I'm very impressed with the look and sound quality of this amp paired with a cheap head unit; sounds fantastic. Hope this helps some.

I put this amp on four infinity kappa 6.5 speakers and my truck sounds so good. It makes a lot of power and very high quality for the money

I really like this amplifier. It give my speakers the kick it needed. I bought new speakers that are suitable for the wattage. It really sounds crisp and clear. I also installed a new head unit. Alpine iLx-507. Worlds apart from my factory radio and speakers. Btw, I just ordered another Infinity 3004a 4-channel amplifier, for my other car. I am impressed by not only the volume but more so the sound quality this amp makes.

First one i recieved was the wrong amplifier. Second one was damaged with loose parts inside.

Please update photos to reflect actual product as they do not match. Other than that 100% satisfied! Great product & value! Would definitely recommend!

Very high quality amp

Resibi el amp sin tornillos se que es usado pero que sea algo útil debo de gastar por tornillos

Tiene muy buena fidelidad para el precio

Buena calidad