The 100s will probably work as good or better than the micros with your amp, but you may well be tempted to go with a bigger amp at some point to realize a real benefit.
Another thing to consider and maybe ask John S. about is that the micros are recommended for near field listening in any room size on the OHM site and the larger Walshes are recommended for general listening in various size rooms.
That's because the larger OHMS are just bigger and CAN go louder for listening further away when feasible in a larger room, but for more nearfield listening in a room your size, there will not be much if any difference with a larger model I suspect.
USing the Musical Fidelity A3CR (120w/ch) I've had my big OHM 5's in the 12X12 room where the 100's are currently. There was no real benefit with the larger OHMs. When I had the 100's in the larger room where the 5's are, there was....mainly the low end had more weight and balance and was more fulfilling at higher SPLS. Other than that the 100s sounded very much like the 5's overall.
I suspect the same would be true in your case with the 100s compared to the Micros.
Another thing to consider and maybe ask John S. about is that the micros are recommended for near field listening in any room size on the OHM site and the larger Walshes are recommended for general listening in various size rooms.
That's because the larger OHMS are just bigger and CAN go louder for listening further away when feasible in a larger room, but for more nearfield listening in a room your size, there will not be much if any difference with a larger model I suspect.
USing the Musical Fidelity A3CR (120w/ch) I've had my big OHM 5's in the 12X12 room where the 100's are currently. There was no real benefit with the larger OHMs. When I had the 100's in the larger room where the 5's are, there was....mainly the low end had more weight and balance and was more fulfilling at higher SPLS. Other than that the 100s sounded very much like the 5's overall.
I suspect the same would be true in your case with the 100s compared to the Micros.

