Will M700s suffice

I have an S300 driving my Martin Logan Motion 60XTi speakers as surrounds for my home theater. Under load moments, the amp goes into fault protection. Specifically, when the woofers are connected…mids and tweets alone are fine. But the woofer section faults the amp. Did the exact thing to 2 different McIntosh MI347 amps.

I already have M700s on order, the S300 is my loaner for now, and will be placed as Rear duty when the 700s come in. But do you guys think the 700s can handle the load? Should I have gone with M1200s?

If the issue is due to an extremely low impedance load even the 1200’s may not like the load and shut down. Class D amps do not handle extreme low impedance loads well. They are good at 4 ohms but not 2.

I believe I tried a torture test scene with my M1200s (LCR) on the surrounds and it worked, so the question is if 700s will be able to as well. Dual 8" drivers on an entry level flagship meant for receivers shouldnt be that hard to drive. I listen loud but not THAT loud.

Thanks for the insight though! I’m just nervous the 700s wont cut the mustard

1 Like

If the 1200’s were ok with the load the 700’s will probably fine too. Good luck!

1 Like

My wallet is really hoping you are correct!

1 Like

I have the 700’s and they are equally rated as musically stable into 2ohms. When looking up the specs on the ICEPower modules that both the 700 and 1200 are based on, they state a min of 2.5 ohms and 2.7 ohms respectively. Now your ML’s actually go down to 2 ohms between 100 and 300 Hz which is likely your problem with the woofers. I doubt the 1200’s would be more stable than the 700’s with your speakers.

700’s drive inefficient Maggies very well, in my case the LRS to insane levels with no problem.


If I may ask how did you figure that out about the speakers?

Take a look at their impedance curve at https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=2238:nrc-measurements-martinlogan-motion-60xti-loudspeakers&catid=77:loudspeaker-measurements&Itemid=153.

I don’t know if this is helpful, but I’ll note that the M1200s I’m using appear to be quite capable of driving my Martin Logan 15A speakers, which supposedly have an impedance drop to about .5 ohm at 20kHz.

But they’re stated by ML to be a 4 ohm speaker, and my guess is it’s a lot easier to drive a low-impedance load at very high frequencies than in the bass range. (I am not an engineer, so feel free to pick that apart.)

1 Like