I have a PB-10 NSD and after turning everything on today I noticed that there is only the faintest sound coming from it. No settings have been changed and i've double checked everything. No matter how loud it is turned up I have to literally put my ear down on it to hear the faintest rumble coming from it..Any suggestions?

You need to ensure no settings on the AVR have changed. The try a different cable. Be sure to turn the sub gain down before you try anything. Should still be under warranty, so contact SVS.