Thanks for Phild's response. I never thought of matching input/output issue before! From Platsolos and Sean's reply it looks like Monarchy 18B is ok in terms of directly driving power amps.
OK, I will go with 18B.
Interestingly, Monarchy Audio company is right in the neigherhood of where I work in South San Francisco! I can almost see their building from my office. A couple weeks ago I went to their office and briefly talked to their chief engineer C. C. Poon and auditioned the 18M. Frankly speaking I can't tell it sounds good or bad since my ears are NOT well trained (yet). But the build quality is obviously excellent! I trust all the user reviews and the advices from you guys. (plus it is on sale for $299 new!)
Again, big thanks to Sean, Phild, Platsolos, Tacs, Billhansen !!!!!! You guys are cool.
Abe