High volume shuts off the receiver

mmmhh, I have a feeliing that your receiver is going into proctection mode. Your speaker have a nominal 4ohm load and most likely dips lower and it can be very taxing on most receiver if played at high volume for a long period of time.

Unfortunately, you have 3 options and none includes keeping your current equipment as is if you like it loud

option 1, keep receiver and change speakers for something a little easier to drive
option 2, keep speakers and get a receiver capable of driving 4ohms steadily
option 3, keep speakers and get receiver with pre outs and an amplifier to drive your speakers.

maybe others will chime in

How do you have the AV receiver setup (in a cabinet, or just on top of stand or such? Also, what are you playing when the receiver shuts off (movie, tv, music)?

^^^^
yeah, I guess I kind of jump the gun a little...

Looking at the spec sheet for them, they should work fine on 4, 6, 8 ohm systems, from what Martin Logan is stating in the manual for them.

Yes the amps put out some heat. And depending on the music, yes it can cause it to shut down. Looking at the spec's for the receiver http://usa.yamaha.com/products/audio-visual/av-receivers-amps/rx/rx-v373_black_u/ it should be doing 160W dynamic with those speakers. So yeah it is working hard at the volume you have it at.

When you set it up, did you run the YPAO first, to optimize it for your room layout? Can you post a picture of the reciever in the cabinet you are using, and also measurements from top of the receiver to the bottom of the shelf above it, and is that cabinet closed back, or open?

I saw that too, find it kind of strange though but hey, I'm no engineer.

Wouldn't there be a possibility of damaging the speakers?

OP, have you tried playing the music at the levels you had problems with the receiver out of the cabinet?

With a lot of bass, or miss adjusted settings, you could. Also not making sure the wiring is connected properly, can be a issue. I think that the overheating was their issue, not the speakers or receiver. My Denon sits below a glass shelf in our entertainment table, with probably two inches of space above, but open on all sides, never had issues with mine shutting down in that setup.

Closing electronic equipment in a cabinet is bad, if there is no ventilation. On board the ship I was on, we had a 5,000 Watt PA tube amp setup, for the flight deck, and that room when closed up was probably around 95 with cooling. When we went to Honduras, it got as high as 130 in the room, but the equipment did its job. Of course we are talking about a different class of equipment, but it comes down to getting airflow to keep it cooled down, and not driving it hard as if you are in a concert.