whats the true power ratings? is it 2 ohm stable mono?

 

The birthsheet on my 40dsm said 92 watts/channel at 2 ohms, I ran mine at 2 ohm mono without a problem for years. Once I even ran four 6.5's, and two 10's off of it. Beauty amps!

 

That's pretty decent for output. Mine I think was in the high 70s. A safe bet would be approx. 80x2 RMS at 2 ohms so like 60x2 at 4. The DSM amps, while not advertised for it, could regularly handle 2 ohm mono loads without issue. Just give it some ventilation room and it should be fine.

 

But below 2ohms not vented properly is how they got the nickname burnt hamburger!

 

^ Really? Never heard that one before. I've used DSM amps since 1993 and never had a single problem ever with them. I've used a 40 and 40i in various ways (4 ohm stereo, 4 ohm bridged, 2 ohm stereo, 2 ohm bridged), a 60 2 ohm bridged on a pair of 12s for quite a while, a 100ix 4 ohm bridged, 200ix 4 ohm bridged, and 4080 4 ohm stereo. I guess I just don't abuse my stuff

 

Bridged mode is made for 4 ohm only.
Wasn't hard to find on the Rockford website
Mono (Bridged) Mode - The diagram below illustrates how to configure most Rockford Fosgate 2-channel amplifiers for mono mode.

 

I bought my 40 new in 94, and it ran at 2 ohm mono for years without a hitch, no matter what the manual says. Just be careful with the gain, and ventilation definitely helps, as stated above^^

 

Yes they do only indicate that its for 4 ohm mono, but it can safely be run 2 ohm mono if you give it room to breathe.

 

^^as with most RF amps, my current p4004 ran initially for 1.5 years with the two rear channels(3&4) bridged into a 2ohm load with no problems except it would get warmer than normal after a long drive(150 miles or so) in the summer at fairly loud levels( highway driving with the windows down). Day to day was no problem at all.