I was looking to purchase a pair of KRK RP5G2s along with a Zero DAC. Could anybody offer me help as to how to set these two pieces of equipment up with a Macbook Pro or give me advice into which cables I need to purchase?
I have almost the exact same setup, except with a Maverick D1 dac and RP6G2s. I'd get an optical cable to go from the MBP to your DAC, and then RCA cables to go from the line-out on your Dac to the jacks on the back of the monitors. Unless you're running cable over a long distance, I wouldn't worry about balanced cables.
Nah, they're not a necessity. Having said that, I started off with what you're planning and ended up using them anyway.
Where will you be controlling the volume from, your DAC? I had a PC -> studio monitor setup, ran 2 x RCA -> XLR from my audio source to a Nano Patch for volume control, then balanced TRS -> XLR from the Nano Patch to my Tascams. That way I maxed out all the volumes and just used the volume knob on the Nano Patch. This setup helped with ground loop hum issues as well (must've been the balanced cabling).