You are running m148 (XLR out) into the Line in (RCA) jacks on the 671, right?
Keep testing, you will figure out what is going on.
BTW, now that you have the VOM, you can test the batteries in the 671 too.
I could not survive without a Volt Ohm Meter. You can check your AC in the house (be careful
) You can check your car battery too. Eventually, you will be checking resistance and after that, you can figure out how to check current draw.
FWIW, you can check continuity in your cables by setting that particular meter on the 200 ohm setting. Touch the probes to coorisponding sides of the cable ground. If it reads anything other than 1 ., there is conectivity. Do the same for the other connectors on the cable. SOme multimeters actually give you an audible signal when there is conectivity. That meter does not. You just have to look at the screen to see what is happening. When I check connectivity, I move the cable around, to see if there is a point where the connectivity is broken. It is more likely that there is a short or a near short in a cable. To determine that, check the ground against all of the other conductors. If you get a reading other than 1 ., than you have a short, and the cable is bad.