Volume control output 3 to 8

[PeterBennen]

Hi,
US 16x08 interface
Is there a way to control volume on lineoutputs 3,4,5,6,7 and 8. I know that 1 and 2 is on the front.

I want to hook up my 2 extra monitors to channel 3 and 4 for my surround sound but have to control the volumes.

Thanks Peter