I have the M50's and like them alot. I don't think that they are a laid back speaker but I can understand why people would describe them this way when comparing them to the M60's. I have been using them with a Paradigm PDR-12 sub , very musical, when listening to stereo music and the pair really has a nice full sound. If you have a larger room get/try the M50's. If you have a smaller room you can try the M3's. I haven't listend to the M3's but posters claim that they are comparable to the M50's. I, like yourself, can't listen to overly bright systems, they just don't agree with me. Definately give the 50's a listen besides, the M50 crew could use another member. Good luck.
