Hi. I'm new to the audiophile community. I received a very generous birthday present over a year ago of (1) a Massdrop Cavalli Tube Hybrid Amp, and (2) a Massdrop LCX + SDAC amp. I've figured out how to connect the power cables, successfully installed the tube, and connected the units to each other (with the tube hybrid amp "downstream." It looks like the community recommends Massdrop Sennheiser 660 headphones, which I'm about to order. 2 questions for the pros: (1) where does my music go into the chain? My friend told me that you can run music from your iPhone into the system but I don't see how. (2) I received a message that I have a $10 credit waiting in my inbox. How do I get to my inbox from the login screen? Any help from the pros is appreciated!