One other issue is driver coherence. It takes a reasonable amount of distance for the sound of the different driver units in the 9NT to blend well. If your friend plans to sit less than 8 feet away from the speakers, he might not be as happy with them as he would be at a greater distance. Also, the 9NT has more bass than any of the other CDM models, so Sugarbrie's comment about listening levels is worth considering. If your friend finds himself needing to turn up the volume to get the midrange to come alive, he may end up with too much bass.
The 9NTs are a good speaker. As with all speakers, their suitability depends heavily on your tastes, your room and your equipment. I haven't heard the M20s so I can't offer you a comparison with them. Good luck.
The 9NTs are a good speaker. As with all speakers, their suitability depends heavily on your tastes, your room and your equipment. I haven't heard the M20s so I can't offer you a comparison with them. Good luck.