I have a Peavey XR 8600 PA, I have tried adding an external vocal effects module into a mic line but it drops the output volume of the entire PA by about 75%. Any ideas why this is?

SOURCE: how to send at same time main mix and alt 3-4 outputs signals

The subwoofer MAY only have a single channel. If so, you would just use either 3 or 4 to the subwoofer.

Normally you would just tap off the main mix. The only reason I can see for using the alts is to have seperate sliders for level control.

SOURCE: how do i connect the cables between peavey vocal

if you mean effects loop try graphic out to ultraverb input and output to power amp in. this will effect all channels of the xr500c

SOURCE: How do i connect 2 monitors to the one monitor

The monitors will have to be POWERED monitors with built in amps.

You can simply use a wye splitter cable to drive the two monitors. Run the cable from the mixer to one monitor and put a wye cable and an extention to the second powered monitor speaker.

Testimonial: "Thanx, just what i wanted"

SOURCE: i have the peavey xr

That's easily done. Simply connect the left(or right) output of your mixer to one of the channels on the peavey. Use any line input. Since the peavey is a mono system, there's no need sending a stereo mix to it.

SOURCE: I have a peavey 8600 powered mixer. If i run

If you run the speakers FROM the main you should have BOTH the effects and the EQ invilved with your signal.