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Discussion Starter #1 (Edited)
My Current System:
Pioneer DEH-80PRS
Polk PA660
Polk MM6501
Polk DB691
Subs...irrelevant

For some time now I've been looking to replace my current amp, the PA660. I bought it used, and it has quite the hiss even with the gains all the way down. I'm looking for something with a bit more power, and much cleaner sound. I was originally looking to get a Polk D4000.4, but they have recently become virtually unavailable. Thus, I am hoping for some recommendations for other good 4 channel amps.

The Amp Must:
Offer at least 100 watts of power at 4ohms.
Be two ohm stable.
Be virtually noise free. (The D4000.4 has a SN ratio of over 100db).
Cost no more than $300. (Does not have to be from an authorized dealer)

While throwing out names is always nice, I would appreciate it if you included a few reasons why you chose to recommend that amp.

Edit: I've found some good reviews on the PPI P900.4. Anyone have positive experience with this model?
 

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How much space do you have? I picked up a Boston GT-4100 from Boston Direct with a coupon code I was able to check out for $223
 

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Discussion Starter #3
How much space do you have? I picked up a Boston GT-4100 from Boston Direct with a coupon code I was able to check out for $223
This looks promising, as class ab tends to sound better than class d (or so I've heard); however, it seems to be a discontinued item.. The PPI is only 190 on sonicelectronics. That's sounding more and more like a good deal to me.
 

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This looks promising, as class ab tends to sound better than class d (or so I've heard); however, it seems to be a discontinued item.. The PPI is only 190 on sonicelectronics. That's sounding more and more like a good deal to me.


As long as the amp is designed decently you won't "hear" the difference between classes. What you may actually hear is the actual sonic signature of the total amp design, not necessarily class dependent. Advantage goes to class D for output capability to size ratio.
 

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If I was buying a 4-channel amp on $300 budget.. probably Alpine MRX-F65. You can sometimes find them for $300 or less online. Alpine's latest designs are very good. It's small, powerful, efficient.

I also second the suggest to take a look at Boston Acoustics GT designs (the GT475 and GT4100). They were discontinued, but you can still find them online. These are supposed to be very nice, but they're kind of big as expected from a powerful 4-ch Class A/B amplifier (at least in case of the GT4100 model).

I also heard the latest SoundStream REF4 amplifiers are pretty good as far as Class A/B gear goes. Again, relatively big size.
 

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Discussion Starter #8
If I was buying a 4-channel amp on $300 budget.. probably Alpine MRX-F65. You can sometimes find them for $300 or less online. Alpine's latest designs are very good. It's small, powerful, efficient.

I also second the suggest to take a look at Boston Acoustics GT designs (the GT475 and GT4100). They were discontinued, but you can still find them online. These are supposed to be very nice, but they're kind of big as expected from a powerful 4-ch Class A/B amplifier (at least in case of the GT4100 model).

I also heard the latest SoundStream REF4 amplifiers are pretty good as far as Class A/B gear goes. Again, relatively big size.
So I looked around for those Boston amps on the cheap, and I didn't find much. However, I did find these: Boston Acoustics GT-2125 (gt2125) GT Reference 2-Channel Amplifier
It looks like this is the two channel version of the same reference amplifier. I can get two of these for less than the Alpine. Good deal? I suppose I'll have to do some more reading. The specs are very impressive as far as I can see. And I could just get one at a time to save my wallet.

Also, is there any specific reason as to why you'd spend more on the Alpine instead of just getting the PPI P900.4?
 

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Discussion Starter #11
Yeah, but I don't really think that the D4000.4 is worth $300. I used to see it for $250.. Missed my chance I guess.

So, about those GT-2125's. Anyone know of any reason I SHOULDN'T use two two channel amps instead of the one GT-4100? The 2125's offer more power, and I have the space. And to add to that they are cheaper.
 

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Yeah, but I don't really think that the D4000.4 is worth $300. I used to see it for $250.. Missed my chance I guess.

So, about those GT-2125's. Anyone know of any reason I SHOULDN'T use two two channel amps instead of the one GT-4100? The 2125's offer more power, and I have the space. And to add to that they are cheaper.
go for it! i am definitely picking up another one!
 

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Yeah, but I don't really think that the D4000.4 is worth $300. I used to see it for $250.. Missed my chance I guess.

So, about those GT-2125's. Anyone know of any reason I SHOULDN'T use two two channel amps instead of the one GT-4100? The 2125's offer more power, and I have the space. And to add to that they are cheaper.
The Boston GT amps are good amps and you can find them for some amazing prices right now. Only downside is that they are big, but definitely powerful and can run at low ohm loads.
 

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For the money it seems you would be hard pressed to find a better value than the PPI amp mentioned. However, if you have the space and are willing to wire up two powerful amps......There are a couple of refurb Soundstream REF2.640 amps on ebay for $169.90 each. These are very nice amps in terms of power delivery, build, sound, and fit & finish. At the refurb price one is getting a lot of amp for the money....even at the regular "net" price they are a good buy. IMO, one would have to spend quite a bit more to jump up to the next level.
Soundstream REF2 640 570 Watt RMS 2 1 Channel Amp Car Stereo Amplifier Warranty | eBay


SPECIFICATIONS

REF2.640
RMS Power @ 4Ω, 14.4V - 2 x 190
RMS Power @ 2Ω, 14.4V - 2 x 320
RMS Power @ 4Ω Bridged, 14.4V - 1 x 640
Total Harmonic Distortion (4Ω power) - 0.02%
Frequency Response - 15-50kHz
Signal-to-Noise Ratio (4Ω power) - 102dB
Damping Factor (100Hz, 4Ω) - >1500
Dimensions: 2.25"h x 9.875" x 16"
Fuse - 80 A

General:
• Sequenced Delays Eliminate Residual Power-Up/Power-Down Pops
• Differential RCA Inputs Isolate 12V/Audio to Ground, Eliminating Ground Loops and Noise
• Full Signal Path Low Noise/Distortion Circuitry Topology
• Optimal Component Layout for Minimal Distortion Induction & Signal Separation
• Triple Darlington Audio Output Stages
• Differential Drives Divide Pre-Amp & Power-Amp Stages, Eliminating Ground Looping
• Full Differential Feedback Surrounding Power-Amp Stages directly from Speaker Terminals resulting in Uncolored Sound Reproduction and Elimination of Ground Loops
• Output Stage Bias Individually Sequenced, Optimizing Sound Quality
• Stout 2 Oz. Copper Traces Effortlessly Transfer High Volume Interna Current
• Close Tolerance Signal Path Components - 1% Resistors & 5% Capacitors
• Final PCB Layout Designs are culmination of examination and fine tuning of all circuit elements to work in harmony as a whole
• Hawkins Boost Control - Proprietary Bass Equalization
• Continuously Variable Crossovers

PSU:
• Pulse Width Modulated
• Large TO218 MOSFET Transistors
• High Volume, Low ESR Capacitance Banks Compensate Power Supply Ripple Currents
• Extra Low Current Drive Stage Increases Efficiency & Sound Clarity
• Individually Regulated Preamp/Crossover Power Supplies Ensure Signal Purity
• Separated Capacitor Charging/Discharging Current Paths Prevent Rail Switching
• Spikes & Ground Traces from Entering Signal Stages Resulting in Distortion
Soundstream - Amplifiers - Reference

Or a couple of the Precision Power PPI P600.2 amps for $139 or maybe one REF for the front and one PPI for the rear speakers?, etc....
 
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