The M-3si needs to be out into the room and is very power hungry. If you can deal with this you will have a fine speaker system. I have never listened to the OM-6's.
Agree with Dave,
I have owned M3si and now own the M5si.. which I prefer..
I also own OM9s that I use in the 2 channel section of my HT system..
The Msi series is a very power hungry and low efficiency speaker and does need to be about 3 to 4 feet away from the walls to get the best imaging.. the OM series has some benefits of the Msi series as far as the tame highs and the depth.. both are very easy to listen to for a long period of time. Bass is more accurate on the Msi series, again you need some power to run them.. Posisition is not as important with the OM series I have found. Musically, I prefer the Msi series.. they are simply better imo.
check out my virtual systems to see what I am running each series with.
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