*roblio
Regarding the X12 mrv-1507 4channel 3600watts, please.. that's quite a generic V12 amplifier (bootlegs in fact of the famous Alpine V12) and it's usually used for powering of separates - not power-hungry subwoofers. Don't buy the 3600W, it does not even produce half of that value. It's doing something like 60W * 4 ohms on each channel.

Isipin mo muna how you'll wire the subwoofer up. Since meron ka dalawang dual-VC subwoofers you have quite a lot of options naman. But to answer your question, kaya ba ng MRV ang 2-ohm load stable? The answer is... no. Most budget amplifiers aren't built that well sa power supply section nila to supply you 2-ohms on bridged mode. If you're doing a mono or 2-channel amplifier, baka pwede pa. But for 4-channels? Nah, they're just 4ohm stable bridged.

Stable on 2-ohms? Probably on a per-channel basis yan. Ex. 60Wx4 * 4ohms, 90Wx4 * 2ohms. But please, don't believe the box. Yun 3600W palang nga linoloko ka na pano pa yun ibang specifications.

Your best bet? Just use one of the voice coils - tutunong parin naman yan and use it on a bridged 4-channel amplifier.

*acgq
Not all amplifiers are like that. It will depend sa power supply section ng amplifiers. More expensive amplifiers are often over-built so they are stable even under heavy load. For example, my Audison VRX amplifier is stable at 1 ohm on a per channel basis while stable at 2 ohms on bridge.

*hypnos
Regarding the FX's midbass, don't worry about it. It's strong enough for 98% of the people who run it. Even if you run sub-less and try to squeeze every bit of excursion sa midbass, kaya parin niya. However, just don't expect outside listening. But for in-car listening? It's more than enough. Don't let your midbass run lower than 50hz, it isn't worth it. Get a subwoofer if you plan to go that low.

For the midbass, how much power it will need will depend on your listening levels. However, I don't believe bitin ang mga tao even with 70W of power. 100W is more than enough.

Oh and heat is the least of your worries. The PDX series are Class D amplifiers and are very efficient - heat issues are practically nonexistent.

*metal_mulisha01
Pano mo masasabi na "hindi ka satisfied sa quality?"

From my point, I think isang problem mo dyan is that you're using coaxial drivers on your doors and a tweeter up front. Yun ngyayari kasi dyan is it's confusing. First is that you hear high-pitched sounds from your dash (assuming nasa dash yun tweet) at nasa paa mo (where most midbass drivers are). Second is that paminsan magkakaroon yan ng phasing problems due to overlapping sound waves. So stick with a separate component speaker muna - midbass at doors and a tweeter on top.

For the others, kaya mo yan idaan sa good installation and tuning.