TJ, 350 watts wouldn't be "noticeable" unless they were actually being used by playing louder. Since it's highly likely that the present amplification can already easily handle all safe(to your hearing)sound levels, playing even louder wouldn't be a good idea. Also keep in mind that the 140 watts would also see an increase into 4ohms to something over 200 watts.

Enjoy the music, not the equipment.