Class D amp MTX vs Alpine

I just got a new honda accord and I want to put my Rockford fosgate Punch He sub (12" 4ohm single voice coil) in my trunk. because I havea navigation I can't add a aftermarket headunit so I'm forced to use a line level converter. I'm looking for an amp ot power this sub (recommended RMS wattage is 200w) I've been looking and found 2 different Class D amps. one is an alpine MRP-M350 and the other is an MTX 421D. the MTX says it puts out 210 watts X1 at 4 ohms at 14.4 volts. but on other sites I've seen the specs of 150 watts X 1 at 4 ohms. how do I know how much voltage the amp will draw? does that constantly change depending on what i needs? who makes a better amp, alpine or MTX? or is there another brand that would do the 200 watts RMS X 1 @ 4ohms that you'd recommend. I mention these 2 because I can get them for less than 150. i don't really want to change my sub as I have a a good box for it and it sounds ok to me (just looking to fill in the missing low notes in my music, I'm not one who wants to SLAM my system all the time) also, should I use a cap in this system? they are cheap enough and if it will any sort of protection to my battery and alternator I'd like to do it. thanks!

-Nick

get the alpine, try putting out more $ for the mrd-m301 if possible, mines put out about 380rms @ 2 ohms

and dont get a cap

I actually found a pioneer premier amp for 99 dollars brand new. puts out 250 watts X 1 @ 4 ohms. so that should be perfect for my sub. thanks again (also I'm skipping the cap)

That mtx would do more than enough power even at 150watts not sure on either rms but when i get a chance il look. The amp can only draw as much power as its given so when the cars off and the keys is on the acc mode it has 12volts, and when the car is running you would have between 13.5-14.5v depending on what your running, headlights, wipers, and what not. If your lights do dim then do a search on the big3 thats generally what everyone recomends ove the cap its supposed to be just as good. I havent had a chance to give it a go my trucks been on jack stands for 6 months.