Need Advice on Small, Powerful Affordable 4ch Amp

Mods, I realize this isn’t a “help” question in the normal sense of fixing something but it seems like this is the most relevant place for this thread. Please move if necessary.

First off, this is for my Impreza, not my Integra. Second, I’m planning to get a 4ch amp (mount it under the driver seat) use 2 channels to drive the front speakers and bridge the other two to power a sub. Here is what I want to power:

CDT CL6 Components
150 rms / ??? peak

IDQ10v2 d2
250 rms / 500 peak

The amp’s I’ve been looking at:

Alpine PDX-4.100
Class D
100x4 @ 4ohm
100x4 @ 2ohm
200x2 @ 4ohm bridged
10.2" x 7.6" x 2.5 (add approx 1+" to width for speaker wiring connectors)
MSRP $550

$150-$200 shipped USED, possibly refurb on ebay
$310-$340 shipped NEW ebay sellers
$200-$260 shipped USED private sellers ebay and elsewhere

Alpine PDX-4.150
Class D
150x4 @ 4ohm
150x4 @ 2ohm
300x2 bridged @ 4ohm
10.2" x 7.6" x 2.5 (add approx 1+" to width for speaker wiring connectors)
MSRP $750

Kenwood Excelon XR-4S
Class D
120x4 @ 4ohm
150x4 @ 2ohm
300x2 bridged @ 4ohm
9.25" x 7.8" x 2.2"
MSRP $499

$250-$270 shipped NEW on ebay all day
$200 shipped NEW private seller

Kenwood Excelon KAC-X4R
Class ?
100x4 @ 4ohm
150x4 @ 2ohm
300x2 bridged @ 4ohm
13.4" x 8.8" x 2.2"
MSRP $500

$220 shipped NEW
$265 shipped NEW

Eclipse XA4200
Class D
125x4 @ 4 ohm
200x4 @ 2 ohm
400x2 bridged @ 4 ohm
12.3" x 2.5" x 10.25"

  • a bit larger than the others, but heard good things so far
  • power/gnd/rmt + speaker wires on one short side
  • line in + audio adjustments on other short side
  • would need to mount horizontally in car, wires wouldn’t be exposed, but seat would need to be removed and amp unbolted to make audio adjustments

$250 shipped NEW on
$430 shipped NEW on ebay

Cadence Xa175.4
Class A/B
110x4 @ 4ohm
175x4 @ 2ohm
350x2 bridged @ 4ohm
14.2" x 10.4" x 2.3"

  • Slightly larger, need to measure to see if it will fit
  • Higher quality sound?
  • Supposedly true wattage ratings

$210 shipped NEW from
$175 shipped NEW from another forum friend

I was also looking at the MA Audio HK598, power is more than I need and I can get one for $150 shipped new. But there’s a good chance it’s too big to fit under my seat. I’m open to other things on the market but it can’t be larger than anything posted above and must be under $300 to my door, preferably only about $200.

So, anyone have any input? I’m leaning towards the XR-4S.

i hate MA Audio. ive gotten nothing but bad products from them; split subs after a few months, ive even seen one of thier amps catch fire while the stereo was off. scary.

on the other hand Alpine makes great shit. their amps all have little fans in them to help with cooling, so shoving it under the seat is thermally safer than most other amps. for me, living in sunny florida with almost 100% humidity some days, this is important to me in an amp. also i feel theyve done much more planning in electrical safety than most other manufacturers. back in the day Alpines amps used to even seperate the entire power section from the signal section inside the actual amp so youd have a physical barrier between the actual amplifier and the nasty electrical signals from cars.

out of those two its really up to you with what features you want. have you measured to see if any of these will actually fit? i dont know subies but i havent really had luck with smaller cars fitting much under the seat. that kenwood looks sleeker might fit better, but i have no opinion, or knowledge, of kenwoods products’ reliability.

good luck, car stereo is quite a saturated market im sure youll get tons of input about this subject.

Thanks. I’m officially crossing the MA audio off the list. I hadn’t really been considering it before but now definitely am not after your response and a similar one elsewhere.

I’m not really too worried about the quality of the others, so past experiences dont matter much. Especially because these class D mini amps are a lot different from older style ones. The Kenwood also has a fan. I never liked Kenwoods before, but these are getting some good reviews. Many people switched from the Alpines and said the Kenwoods sound better.

As for space, I think I have around 14" x 12" x 3.25" to work with. But that 12" is a max, I’d much prefer something closer to 8-10" because that will keep the amp away from rear passenger’s feet.

I’m actually having a hard time finding good comprehensive informatin and reviews about the amps mentioned… and I’ve been cruising all the mobile audio forums I can find. Coming here is sort of a last resort since the audio community here I think is fairly small - but I know and trust G2ic, so maybe quality over quantity?

hey man i wish i could help you better but heres a great forum for everthing car audio “Realm of Excursion .com”.:rockon:

Thanks, but apparently that site sucks just as much as all of the other audio sites I’ve seen, actually worse. Just searched for “xr-4s” “xr4s” and “pdx” not a single post came up… wtf is up with these audio websites? Maybe I’m just spoiled w/ g2ic, h-t, nasioc, and nwp, shit even howard forums (cell phones).

I have never been a fan of regular Alpine products. But if you have the cash the Alpine F-1 series are outstanding. But good luck finding an authorized dealer who carries it. But for the price i would go with the JL 4-channel amp or the RockFord 4-channel. (not the punch series either) But if you look hard i mean really f#@$ing hard you should find the old school RockFords i mean the old, old, old, school amps that were built by Arizona state college students in their dorm rooms.

—I jumped off the JDM bandwagon. Now i walk my own way—

Yeah, the JL HD’s are nice from what I’ve read, but they’re expensive. Like I said in my post, I need to keep it under $300, and even that is a stretch, the closer to $200, the better. At this point I don’t need the biggest and the best, but I do want to get the best deal w/in my price range…

Oops never read the part where you said you want to keep it under $300.

—I jumped off the JDM bandwagon. Now i walk my own way—

You are going to have a problem finding the amp to drive the speakers you have properly for $200, anything in that price range will either be underpowered or just a crappy amp.

Of the amps you list the Alpine PDX-4.150 is your best bet, it has very good SQ and it is the min. 2x150W RMS you need for your CDT component speakers and 1x300W RMS you need for the sub.

The Kenwood Excelon XR-4S, although also a pretty good amp, is at 2x120W RMS underpowered by 30W RMS a channel for your 150W speakers.

You may also want to look at some MTX amps… 94

fcm, you’re just one of the guys I wanted to hear from, thanks for your reply.

I was initially liking the PDX series, they were getting good reviews until I found out about the Kenwoods. I found many people liked the sound quality of the kenwoods above the PDX. Many people were having issues w/ the noise floor on the PDX and really only noticed once they swapped to something slightly better. I pretty much took the PDX off my list after looking into this more, plus it’s above my budget (the 4.150 at least).

I realize that I’m not going to get a perfect amp w/ $200, that’s fine. I just need the best I can get w/in my budget. Originally I wasn’t even going to put any money into this car. Then I stumbled across an underseat box I wanted years ago which are impossible to find. So I bought that. Originally I was going to bridge a 2ch amp I already have but figured since I was doing this I might as well upgrade a bit and see if I can get some power to my CDT’s as well. Currently they’re just running off head unit power, so anything will be an upgrade.

I also found a good deal on a Cadence Xenith Xa175.4 for under $200 shipped new. Any input on that? (still need to confirm it will fit) And I didn’t see anything that would work on MTX’s site. Either way out of budget or under powered more than the ones on my list.

Don’t get me wrong, although I am a firm believer of “it’s better to be over-powered then under-powered” any increase is RMS power to the speakers is a good thing, and driving the speakers with even a 2x80W RMS off-board amp will be a huge improvement over HU power, [less then 2x20W RMS].

I have not heard the Cadence Xenith Xa175.4So I will not comment on it other then to say I like their home audio and the amp does have the 1x250W RMS for the sub. 94

I have installed a few PDX and everyone I installed them for has loved them. The 4.150 is alot of power, too much for CDT. The price margins are really good so the cost is actually pretty cheap on the PDX. The 4.100 is around $300 new and would work really well

The Alpine MRP series actually does pretty well and about at your $200 mark.

I never messed with Kenwwood amps

Eclipse amps have never been that great and no one I have installed for has been happy.

Cadence used to be junk, I don’t if that has changed but I consider them swap meet stuff

The CDT CL series 6" component speakers are at least 150W continuous, [RMS] so if anything the Alpine PDX 4.150 is under-powered as it makes that 4x150W RMS @14.4V, so somewhat less @13.5V. 94

Well, I ended up going w/ the Kenwood XR-4S, it came today (very fast shipping!). Out of all the searching I did it definitely seemed like this amp had more pros and less cons than any of the others I had been considering. So I hope I’m happy.

My first impression: damn, this thing is tiny! Over the weekend I looked a bit better under my seat and I actually have more room than I had initially thought. But it’s good I’m going this small, cause now I think it’ll be so small that even if someone is in the back they won’t be kicking the amp at all, probably won’t even know it’s there (same can’t be said for the sub under the passenger seat).

Really, I think this thing will be plenty good. Last time I had power running to these speakers (CDT’s and IDQ10) each was run off of a Coustic 215XR which only put out 75x2 or 180x1. So this will be an improvement for sure. I’m planning to do the install over Thanksgiving weekend, so I should know fairly soon.

Thanks to everyone who helped me on my decision!