I think there are some misconceptions here:

1. You can't bridge a headunit....first and foremost.

2. You are misinterpreting the specifications on your amps and your speakers....take a second look at all of them...where you see "MAX" next to a spec....cross it out, and find the corresponding "RMS" or "continuous" number...that's the value you should always look at.

3. Your head does NOT make 52 x 4. Take a look at the fuse rating on the head, and the size of the power lead....then take a look at it's size. By those calculations, it's a "200 W amp." See if it's 2/3rd of the size of your external amp...I'm betting it's quite a bit smaller while at the same time it incorporates a CD player, tuner, EQ, some silly screen savers, etc, etc....the only way that head can make 52W per channel is if it gets hit by lightning or it's being driven very far into distortion.

Now I'm not saying your head is bad, it's just a common misconception (and great false advertising) that headuniits actually put out what's printed on the face plate. It's sorta like going to the computer show and buying a set of 300W computer speakers for $10 and they only weigh 3lbs each.....

My suggestion....run the components off the amp, then run the 6*9's off the headunit.