I've recently gotten into audio and whatnot and got a pair of Sennheiser HD 650s for Christmas and now today finally based on recommendations my Maverick Audio TubeMagic D1 Plus DAC w/ OPA627 OpAmp & GE5670W Tube has arrived and I'm a little confused about a couple things. First off, I have an iMac so there's not many options are far as output goes so currently I have the USB chord plugged in and feeding them through that. It also came with a seperate chord that I believe is used for Optical/Coaxial but I am not sure how to use it or what its functions are so if anyone can explain those to me that would be awesome. Is there something else I should be using or buying in order to get the best quality out of these (cablewise)? I have read that while USB is okay it's not going to give the best quality especially for 24/96 vinyl files etc..Also, the voltage options on the D1 are 110V or 220/240V, does that make a difference in anything?
I know I'm going into this somewhat blind but any help that can be provided would be really appreciated, thanks!