406 is correct provided that your speakers are full range. Otherwise, consult your speakers manual/information to meet your needs. In fact, some modern AV amp can automatically detect and set your speakers settings.
I am using Denon. Auto setting will detect automatically.
Of course, you can set it manually. Basically,
If you want the speaker to handle low frequency, such as lower than 120 or 80. Set it to large. Otherwise, set it to small.
Indeed, such setting must be matched with the other setting for SW