Volume levels via Bridge vs USB


I get much more volume playing via the bridge than by usb. Can anyone tell me why this is?

It’s just as well as I much prefer the audio quality via the bridge.But I haven’t figured out how to play movie sound via the bridge.

I play direct to power amps (no preamp) and have barely enough volume for movies. I’m waiting for the DS upgrade kit which has a lower output level and worried I will have to buy a (d*mn $$$) preamp.

BTW I play everything from jriver 19.