Back when i had my pair of S-1's i remember having conversations with other members,,,,, the SB16 had approx 2.5 DB's more output than the SB13-U that i had (which is pretty much the new SB4000's output equal.) i was considering the SB16 until i saw the how much more output the S-1's put out. Also the SB16 does dig a bit deeper noticeably than the 4000.
-Funk 21.0LX Master/Slave combo 4800 watts RMS/9600watts (peak)-
-Chane A-2.4 L/C/R
-Chane A-1.4 side/rear surrounds.