Hello and welcome, oasis! the popping sound you are referring to are probably related to power supply. You can try a different one, (a better one, I hope lol) with more Amperes. Or you can use a power supply to feed your dac, such as this :
http://www.aqvox.de/usb-power_en.html

Very expensive indeed… If you're familiar with diy you can find lot of high quality projects for this purpose. If you're interested let me know! Others will be interested about this…

I know… The trick here is made by detaching the 5v power rail from the usb cable that comes from the pi, and pluggin it in another 5v power supply.