--Crosstalk issues:
Isn't SA250 dual mono? If you use an analogue than crosstalk is already in the phono cartridge that cannot be reduced even with monoblocks. What is your preamp?
--You will be able to add 3...4 decibels to the loudness
--Larger power = larger bass control that could even drive speakers to exceed their bottom freequency bandwidth border.
--Monoblocks are more current efficient due to dedicated PS on each.
--Consider that if you exceed enough than you simply lost money. Isn't SA250 alone already takes off maximum your speakers can perform?