Mario, welcome back. The commonly suggested 80Hz crossover setting is what I use on my M22s although I have available 40Hz-200Hz. 80Hz has been found by THX and others to be a good compromise setting, being high enough to relieve the speakers(and the amplifier driving them)from a significant part of the lowest bass burden while not being so high that the sub is easily localizable. No, don't set the M22s large and don't use a "plus" type of setting. Use bass management to allow the sub and speakers to handle the frequencies which they're best at.
