Did I make a speaker/receiver mismatch?

OK you like the way it sounds.
That is the only thing that really matters.
As long as you don't play the system to loud you won't have any issues.
If you keep turning up the volume and the sound starts to change and sound bad, stop and lower the volume.
If the AVR shuts itself off that's also a sign that you are playing too loud.
Chances are you are going to be fine.
Enjoy your new gear.

Never hurts to get a 4ohm rated AVR and the salesperson should have matched your gear as that's part of their education.

That being said, see what you can do to find in an AVR that's 4ohm rated or return both the AVR and the Martin Logan's, pick up another 2312Ci and a pair of 8ohm matched speakers and be done with it.

Do you have a clean wire hook-up to the speakers and receiver > did you hook-up with
bare wire, or used somthing like banana jacks. Sometimes bare wire strands cause a
receiver to shut down. Also, could be a defective receiver.

However, the Denon is also strong at 6 ohms. Some Martin Logan speakers can be a
challange for receivers.

Is -50 loud?

Yes, big mistake. You have to match the speakers with the Receiver's ohm rating. Like BeeMan458 said the sales or tech support at best buy should have caught this while making this sale. Also for long term system stability ensure that the wattage ratings also match. A receiver with a low wattage feeding a high capacity speaker will also kill your speakers as you will keep pumping the receiver for a higher sound volume. Unless you know what you are doing try to play safe by ensuring your receiver wattage matches 100 to 120% of the speakers load handling capacity.

Loudness is subjective and will vary with your receiver and speaker combination. -50 does not mean much without knowing your system specs. Your ears are the best judge here.

If you are hearing distortion from your system then it is too loud for your amp/speaker combination even if you perceive the sound as low volume.

A high capacity amp can play a lot louder and sound more pleasant then a low wattage amp. When the music is clean with very little distortion your ears won't perceive it as loud. And a lower volume sound with distortion will be perceived as loud by your ears.

This is the first thing I would also check. Given the relatively low volume (if I read -50db correctly), I didn't think it would cause the receiver to go into protection mode. But "-50db" don't tell us much. Not sure if autocalibration was performed, what the trim levels are etc...

Arent' those speakers relatively sensitive? I guess I don't understand impedance in relation to sensitivity as well as I thought. Perhaps there is no relation. Maybe someone could link a post or give a brief explanation on this, I think it could help the OP and others make more informed decisions and not be at the mercy of BB salespoeple.
Edited by jproy13 - 8/30/12 at 1:29pm

-50 db tells us it was playing at 50 decibles lower than reference. So I would not think this was too loud no matter how the volume control is calibrated. On my AVR, Pioneer SC-25, you would hardly hear it. I usually watch television at -22 db; movies -18 db. I don't think it was the volume - some other problem.

Also, count me in as one who thinks the Denon 2312 you have is not adequate for ML 4ohm speakers. I would be looking for something rated into 4 ohms if you really like the ML's. Or stick with Denon and look at a 8 ohm set. Good luck and hope it all works out.

That AVR should handle the MLs without issue unless you get crazy and drive them full blast for hours. I demoed some Motion 12s at a BB Magnolia running off a lower end Yamaha without any issues and it was cranked up.

Then again, maybe the Yamahas can handle lower impedance better than Denon.

I've run Onkyo (809 and 818)and Yamaha (RX-A1000) receivers with 4 ohm Emotiva speakers (88db sensitivity) without problems. Might want to try something along those lines if you are set on keeping your speakers. Sensitivity is more important than Ohms I believe.

nope, sorry... that's simply not true... while some difficult loads (which are defined by more than simply nomimal impedance, there are other factors such as phase angles in play) may present an amplifier with something they cannot handle, the great majority will not run into this issue... primarily because they will never turn the volume knob far enough to the right for it to be an issue...

part 2 is not true at all....

imo/ime... if most posters who worry about "ohm ratings" had never discovered avs, they would never have worried about it, as it will never effect them... too many people jump into these threads with "advice" and "scare stories" that have no relevance in real world usage... also, some confuse their previous experience with tube amps and ohm taps (where it does matter) as being relevant with ss amps...

the avr has a very good way of telling you you are over stressing it... it will go into protection...

That depends on the type of protection used by the amp/receiver. If it's a simple heat/current sensor that shuts the amp down when the current draw is excessive then how loud you're pushing it comes into play. But more sophisticated protection devices will detect too low an impedance load even with the volume quite low, even off in some cases. And some speakers present more problems than others even of the same rated impedance, so the safe route is to make sure the amp is rated for the load.

I guess it depends if you can you find some 8 ohm speakers that sound as good as the ML12's to you?