A few amp choices for my build...

Ok, I know I don't have one of those huge dollar builds or something, but here's what I'm doing:
I have a box with two subs, Pioneer 400 watt (peak I believe) under the passenger side seat. I had a nice Clarion marine amp that ended up DOA from a member on the other site.
I have made a very nice board and setup for that amp, so I am looking to replace it within the same size etc.
I have narrowed it down to 3 amps from Amazon, by the fact that they fit in the hole from my custom build, aren't too big power-wise to be too big for the 8 ga. wire I ran (although maybe pushing it, it's only like 3 feet!)
and they are decent brands with decent reputation.
If you have other suggestions, let me know! None of these are marine amps, but it shouldn't be an issue in my case. Another amp will be added later when I can afford a tower and speakers. If you suggest another amp please suggest which one of these is good as well. (prices on amazon, but these sites had better descriptions)
Thanks!
Amp 1 - the cheapest, but the closest to the watt ratings.
MB Quart OA800.4 $121 on Amazon. http://www.sonicelectronix.com/item_67853_MB-Quart-OA800.4.html

• Max Power Rating:
  
  • 4 ohms: 100 watts x 4 chan.
  • 2 ohms: 200 watts x 4 chan.
  • Bridged, 4 ohms: 400 watts x 2 chan. - Note: max power rating, so max on subs is 400 as well, good match, or do I need more amp and turn it down?
  • 1 X 60 amp fuse btw

Amp 2 - A bit more a $179 Kicker 10ZX650.4 http://www.crutchfield.com/S-oENylic9fe9/p_20610ZX654/Kicker-10ZX650-4.html

• 120 watts RMS x 4 at 4 ohms (160 watts RMS x 4 at 2 ohms)
• 320 watts RMS x 2 in bridged mode (4-ohm stable in bridged mode)
• 2 X 40 amp fuses btw

Amp 3 - Most expensive, but Class D $189 Rockford Fosgate Prime R600-4D
http://www.crutchfield.com/S-F9dye1co9AB/p_575R6004D/Rockford-Fosgate-Prime-R600-4D.html?XVINQ=DST&XVVER=CCC

• 100 watts RMS x 4 at 4 ohms (150 watts RMS x 4 at 2 ohms)
• 300 watts RMS x 2 bridged output at 4 ohms (4-ohm stable in bridged mode)
• No built in fuses but recommend 60 amp in line

Thanks guys, I know I'm going a bit cheaper this way without marine amps and such, but if you can find one that's a good name etc. I'll consider obviously. I would prefer amazon as I get a 3% discount on anything there, and I enjoy the return policy/guarantee I get there along with free shipping.

Look at the JL Marine Lineup. They have top notch products.

If your budget is minimal, go with the MB Quart amp. I am in the middle of a rather large stereo upgrade, but doing it on a moderate budget. I already had one of the MB Quart amps left over from my other boat and was thrilled with it so I went ahead and bought another for this build. Just yesterday I finally got it hooked up and it ROCKS (just have to mount the board and tidy up the wires in the helm). I have a 4 channel that i am bridging to the tower speakers (probably finish those later this week) and a 5 channel doing the cabin speakers and subs. With that said, when/if I do upgrade amps, I am looking in the direction of the Rockfords. They seem to be a good value for class D. If my budget was unlimited, I'd go JL, but like you, it is not.

I am on my second boat with pioneer car amps, class D. No complaints….

I looked at the Pioneer amps, but they were all squares and didn't fit in the hole I have for a cutout. I have the amp setup so it's recessed into the board and then also so that air can pass through the fins etc. that way so it's open on top and bottom. I like the RF because all my wires can come from the bottom and be hidden as well. The MB Quart is a nice piece as well. They really all are. I think the MB is cheap due to being a little less power and being discontinued for a new model.

I think I would do the MB #amplifier of the ones you listed. It is the cheapest and all of the powers are comparable. I would be suspicious of anyone who would claim to be able to hear a 20 watt difference in amps. So, if it is all the same, why pay more?

I also forgot!
How does a MONO amp work. I see them all over. Is that to drive one big subwoofer? Since I am runing two subs, would you run a mono block amp to the subs in series to get a 8 or 2 ohm load or something? Just a little confused on that. I've done about a dozen installs on people's stuff before, but never a mono amp to two subs. Always got a dual or quad channel amp to the 2 subs.

Are they 4 ohm #subwoofers ? If so, running in series will give you an 8 ohm load. Parallel will give you a 2 ohm load.

Yes, a mono drives a sub only. So then you need to look at the specs on the amp to see if it will drive 8 ohms or 2 ohms. I believe most will.

Avoid the MB Quart because there is no mention of RMS or CEA-2006A. 'Peak' or 'maximum' power ratings have zero basis in reality as there is no such rating standard. Raises integrity questions. So you have no clue as to how much power you'll get.
If choosing between Class AB and Class D in a boat, I like D. 60% more efficient makes that power wire and battery look bigger.
Btw, if I was driving only two 4-ohm woofers with the amplifier, I would use a monoblock.

Any good monoblock will be 2-ohm stable. So you would parallel the two 4-ohm woofers to achieve a 2-ohm load.

Thanks guys! As this is strictly for the subs, I will start looking at Monoblock class D amps. I do worry about the temperatures because we sit a lot.
Also, I had the same concern about the MB, but the 60 amp fuse hinted at more power available than it's letting on in the specs. Or they are just using a really big fuse for no reason. I believe a 60 amp fuse is good for like 400 - 500 watt rms?

The fusing is not an accurate indication of power. Fuse sizing may be selected for protection against a catastrophic failure and not maximum consumption at full normal operation.
You can't apply Ohms Law to the calculation of an amplifier's output power in a strict sense. The efficiency may be 25% at low power or 60% at max power. And the efficiency goes down from there as the load impedance is lowered.

I want to back up on few things I said earlier. I never clicked on your links so I assumed the MB Quart amps you were referring to were the marine ones that I have. I like my amps and for the money, they perform really well IMO. They are also rated in RMS power. If you can afford to go with class D from the beginning, its probably a good idea with the charging systems on our boats. I WILL be upgrading to class D eventually just from an efficiency standpoint. If you are only powering subs, mono block is definately the way to go.

http://www.amazon.com/Rockford-Fosgate-R500X1D-1-Channel-Amplifier/dp/B00BF6HYDE/ref=sr_1_3?s=car&ie=UTF8&qid=1395626882&sr=1-3&keywords=amplifier
Ok, so I'm on to something more like this...
500watt rms X 1 @ 2 ohms. This would be really mean 250 watt rms for each sub, correct? Both subs wouldn't see 500 rms watts? Just trying to figure it all out, lol!
It's funny because I've done so many sub installs but never messed with this mono-block amp stuff!

Correct.... the two subs would split the power

I know it's not on your list, but I love my Alpines....I picked up my sub amp on ebay for $180...they are rock solid, small as h*ll, and extremely efficient....

if your completely set on the 3 you listed, I'd go MB Quart....good amps at a good price

Well the amp came in on my birthday and I installed today.
This Rockford Fozgate amp is awesome!
It's also half the size as the clarion with almost the same power rating! Guess I got room for another when I get the tower.

Yeah... I got in trouble for waking up the baby.