SimHub freezes when 2nd Nobsound is added.

I have no problem using a two channel Nobsound amp to drive two Dayton bass shakers.  I attempted to add a second Nobsound to drive a third bass shaker however when in the Sound Output area to set up the cursor freezes for 30 seconds when trying to test the output and game does not run correctly.  I see online where many people claim to add additional sound devices (Nobsound) with no issues.  Thanks for any help.