I assume it is a switc to clean up frequencies less than 50hz (turntable rumble). Either way you have one of the best loudspeakers out there.
I am not a huge Bose fan, but that speaker is awesome.....
YA you bet!!, I LUV EM, wifey not so much, something that makes more noise than her and she cant compete!!
OH YA, I luv my 901's
what was that honey?????