jrbdmb

I'm looking for an upgrade on the factory speakers in a 2011 FX4, and after much back-and-forth I've narrowed the search down to the Polk DB series (DB571) or Polk MM series (MM571). I've ruled out the Infinity Kappas because I'm concerned about how their 2 ohm load will work with a mediocre HU, and because the treble may be a bit too hot for my tastes. I also considered the Boston Acoustics speakers, but the S85s seem a bit cheap and the SC85s don't have much in the way of reviews or comparison tests.

I'll add that I won't be pulling the factory HU with Sync anytime soon, and I want speakers that will play well with the factory HU until I get around to adding an amp. I'm leaning towards the Polk MMs, but I'd appreciate input from anyone who has heard both (or can compare these to the Bostons or Infinitys). Thanks.

Note: both are 5"x7" two-way designs. The MM571 has a slightly larger 1" tweeter, glass fiber woofer (as opposed to polymer/mica for the db571) and goes down to 38 Hz (52 Hz for the db571). The MM571 is a bit less efficient but can handle more power. But the MM571 it is quite a bit deeper than the db571 (2 9/16" vs. 1 3/4") and will not fit in the back doors of my F-150. At best I can get MM571s for the front and db571s for the rear, but I'm not sure that mixing speakers like this is a good idea.

Nobman

I have the Polk Audit Db571's in my truck... and like the sound, but the volume still was not enough so now I added an amp and a single 12" sub. The Polk Audio speakers still sound good but with the sub and amp added it give me the sound I was looking for. I too still have the stock head unit.

I added a Kenwood KAC-8405 Hi level input amp. and a sony Xplode sub.

jrbdmb

After some thought, I will probably go for the db571s ... they'll fit in the front and back, and will sound OK with the stock HU and even better once I get around to the amp.

RES4CUE

i did a ton of research on the Infinity Kappas, they are rated 2ohm but with the way they are set up for use in place of stock speakers, the HU see's a 4 ohm load. Trust me I was stressing when I got them. I saw them on amazon for $66 and snatched them up quick, well they got here and it said 4ohm on the box but in the paper work said they were 2 ohm. I searched high and low, contacted crutchfield and contacted Infinity and they are designed to work with stock HU or aftermarket HU without amplification.

I am confident enough that I have another set on the way and will have all 4 in the truck next week. They have gotten really great reviews. Also they have a switch on the tweeter that you can take out 3db if they are too "bright".

http://www.crutchfield.com/s_1086829...9cf.html?tp=93