SA 400.4 4-Channel Digital Car Audio Amplifier, 400W RMS 2 Ohms Stable, Compact Class D Multi-Channel Amp with Crossover & MOSFET Power Supply, Full-Range Sound Quality

Amazing little amp worth the money. The power is enough for what I need and I wanted something small and compact cause my car doesn’t have much room in it and I need as much room as I can. This little amp powered 6 1/2 inch sub and some door speakers. It hasn’t got hot enough to shut off or anything sounds good. I can’t complain. I wish it had a soft start because you do get a pop in the beginning.

My 1997 Del Sol does not have much space. Heck there's not even enough space for a decent cupholder. But this amplifier fit easily down the center console with room to spare. I've got it connected to the four 6.5" 2way speakers. The extra power from the amp, made the speakers sound fuller with all the different types of music I listened too. I am not an audiophile. But, I am very happy with this cost-effective solution. the only issue I ran into was that the left and right connections were reversed for both the front and rear channels. I just had to reverse the RCA's and it worked fine.

Purchased for our boat, currently only have two 6.5" speakers hooked up to it and it gets plenty loud even swimming it's still very audible. Installation was easy, however, I did have one complaint and that was the correct way to wire the speakers. The instructions say +,-,+,- except you only have 3 terminals. I found that hooking it up like this (essentially in series) did not produce even sound out of the speakers. I ended up using the middle terminal for negative and positives on the left and right. I also chose to use 10 gauge for the power run since it's about 20' from the battery to the amp. A heads up to anyone using 8 gauge - DO NOT tighten the set screw down too much, mine stripped out on the negative. I'd recommend sticking with 10 gauge for the power run if possible. I set the amp using a DD-1, It had pretty clean output at nearly full gain before clipping with my Boss head unit. After a full day of boating the amp was pretty hot, keep this in mind for anyone mounting around plastic or an ignition source.

Do not underestimate this tiny amplifier. Wired it to my factory subwoofer and rear door speakers in my vehicle. And it unlocked the power out of the factory sound. Great product for the price.

Great amp for the size! It’s about the side of 2 stacked decks of cards. It’s puts out great power. I’m shocked at how much better my Orion speakers sound now! If you want a cost effective amp, get this one! You have nothing to lose.

Super small size to drive two speakers worked great! I added speakers that were factory options and needed to drive them. This worked perfect and gave me exactly what I needed, sound without blowout. I would definitely recommend!

Very small and worked great

TL;DR: The internals are limiting the capability of this amp from becoming a 5/5 product. Pros: Affordable, Small Build, Simple Set-up, Good Power, Good looks. Can't find a cheaper amp than this one that is also in this small of a package. Drives my 6x9 pair and 6.5 components really well. Can't say the same for tweeters. Cons: Hiss on Tweeters (or any high sensitivity drivers), A shared "ground" between two channels. I was so impressed by them driving those woofers that I bought 3 more before I tested this on my tweeters and midrange coaxials. Thank the heavens for cancellations because I dreaded to hear that hissing sound coming from my tweeters. I have a DSP that can output more than the 4v output my Head Unit delivers on the RCAs so it's not a noise floor issue. I unplugged the RCAs and the hiss was still present. From what I have learned, this amp does not have a good filter to come along with it meaning it will produce high frequency noise regardless of how much voltage you pump through your RCA. Granted, the noise was low enough that you could probably drown it out if you haven't done any acoustic treatment to your vehicle and are always traveling through highways. If you are younger than me (31), it would probably be more apparent to you but for me, the noise is evident enough for me skip this amp and give it a 3/5. If you are older, you probably wouldn't even notice the noise and if that is the case, enjoy this powerhouse!

The size of this amplifier is small enough to hide and powerful enough to run my motorcycle speaker setup. The con that I find is not being able to adjust the hi/low frequency cut-offs