i've had this amp installed for nearly a week now, so i just thought i'd throw my impressions of it out there for the public to see. for the price (i paid $140 from sonic electronix) i personally feel that you'd be extremely hard pressed to find a better 5 channel for the money, if you can even find any others at that low of a price. i made up my decision to give it a shot without really shopping around to find any others cheaper, for the simple fact that any others that might be cheaper aren't from any reputable brands.
i'll start off with a few gripes i had:
#1, there's no manual. i don't recall seeing a manual in the box, and there's also not one available online.
#2, no subsonic filter available on sub channel.
#3, lowpass filter can't be turned off on sub channel.
#4, when installing the amp, i found that mine didn't have a sub +/- printed on the output side of the amp. rather, in it's place, there's the remote in and remote out connections. these were indeed the sub outputs, and i just noticed tonight that ppi's website and sonic's website both show pictures of the amp with 5 channel +/- printed on it. i'm not sure if i just ended up with a bad run as far as the printing goes for that, or if i got an early run before they realized that they had copied the printing from the 4 channel. either way, the amp works fine, i don't care what it says as long as it works :)
there are a few quirks with the amp. it uses harnesses for the rca inputs, as there's literally not enough room on the connection ends of the amp for them. they work okay and i didn't have any issues with them, but depending on your install, particularly if you're going for an install that will show the amp, you may not like that. also, since the remote in and remote out connections are used for the sub output, the bass control knob harness has the remote wire connected to it which just needs crimped/soldered to your turn on wire. simple enough. the bass control knob does seem well made and is pretty linear, except for at the very minimum which damned near shuts the 5th channel off.
in my system, it's running some hat imagines in the front doors that are running coaxially and passively. i have the amp bridged to them, and then it's running a ported sundown e8v3 d4 at 2 ohms in a .56 cubic foot box, tuned to about 35hz. the amp has gobs and gobs of output in this setup (rated 160x2 and 350x1 in this arrangement) and has no issues driving the imagines to their limits. the sundown gets plenty loud and low for me, and is very musical. it seems to actually have more balls than the kicker zx400.1 that i initially tested the sub on, though that amp was in my girlfriend's '98 civic with the sub sitting in the back seat (tested for 30 mins to make sure it was wired properly and was functional) and this is in a 2013 honda fit, so obviously cabin gain is a bit different. regardless - plenty of output for an sq system :)
in terms of noise, well, there is none. at least in this setup. it's being driven by a pioneer avic 5000nex and i use the source level adjuster to +4 for all of my sources so that i get higher voltage out at lower volumes, because boo to buttons for volume rather than knobs!!!!!! :mad: the gains on the front channels are roughly halfway, if i remember right. and again, it's dead silent.
for sound quality purposes, i can't really compare it directly to anything as i haven't had another amp in the car for a direct comparison. i can say that i don't hear anything out of the ordinary. the imagines use to be in my girlfriend's car, running active off of an 80prs, with a ported jl 12w3v3. imagines were powered by an alpine pdx-f4 and sub by the kicker zx400.1, and i'll be honest, the fit sounds a lot better already, even passively while running coaxially. if you really want to hear it, fine - mosconi's and jl hd's, among others, probably sound a bit better. and i would certainly hope so, given that this thing is 1/10th the price and half the size. what i'm getting at is, if you're in the market for a $140 amp, just get this one - it won't be the weak link in the setup. :)
and lastly, heat! anyone that's familiar with the honda fit knows that there's not a lot of room under the front seats in terms of height before you hit the bottom of the seat. this is because the gas tank is up under the front seats. so, mine is mounted to a piece of aluminum that is bent up and around the front of the amp to keep the floor mat off of it. it results in a 100% stealth appearance that also helps protect the amp from feet. unfortunately, being under the seat in such a tight space isn't all that great for heat. so, how does it do? extraordinary. i attended the NC meet which is an hour and 30 minutes or so from my home, and on the way home i cranked it up to the max, had the heater running the whole way on feet (there is a vent under the seat blowing at the amp) and didn't turn the volume down until i parked the car - a torture test, if you will. i put my hand on the amp, and... barely warm.
now, i will put a bit of bad news for the amp out here. the i520.4 was tested by someone else and was found to be drawing slightly more than its fuse rating in amperage to deliver its rated output. the i640.5, being rated at 160x2 and 350x1 in my setup (which oddly adds to 670 rather than 640 - i'm curious where 640 came from?) would need to draw about 46.5 amps for max output at all channels, but it's only fused for 40 amps. i know not to judge amp output by fuse rating, and i'm sure that it can easily reach the rms output ratings on dynamic peaks, but as far as continuous output, i'd say it's a bit of a stretch. still, it's got plenty of power for a modest system. shoot, claydo demo'd my car and anyone that's heard his car can say that he definitely likes it loud, and he was impressed by the amp AND the sundown 8 :D
i guess i should post a few pics...
http://i.imgur.com/tKtLwlTl.jpg
the amp with a ps3 controller for size comparison.
http://i.imgur.com/6dYao1yl.jpg
this picture shows the view of the floormat under the seat with the amp mounted. unless you were looking closely and comparing the floor mat to the other side and noticed this one ramped up slightly, you'd never know it was down there.
http://i.imgur.com/1syaawXl.jpg
the visible part of the amp rack with the floor mat pulled back and the seat still in a normal seating position.
http://i.imgur.com/P2gPhDAl.jpg
and here's what's visible with the seat all the way forward. this picture also shows the mounting for the amp rack - just the two bolts with big ole washers going through the little brace. the thing is very solid. credit for the rack go to chithead, the placement under the seat was my idea but i wasn't sure of the best way to go about it. the metal rack bent over it was his idea and he also fabbed it up for me and came up with the mounting solution.
hope this review and these pictures help some people out - i've been very pleased with the install as a whole, and especially with the amp. there's no telling how long it'll last, but it feels solid, so i'm hoping to get a good length of time out of it :)