need a better sound source?

Thanks to all of your advice i bought a mega turntable; and Sennheiser HD7 xx with the cavalli tube hybrid. I've only listened to the phones with my NAD system and nearly cried (literally) when I heard new levels of clarity on a James Taylor record that I never heard before (i've lost significant learning in the upper range - hence the emotional response) So my question relates to listening music out of the computer. I use iTunes and everything is downloaded from cd at the highest quality and have a dragonfly plugged into a usb port, which will then be plugged into the cavalli. I assume that listening trough a MAC with a Dragonfly is not going to give me theist sound out of my phones. Do i need need sound source ? Expensive cables from house to the cavalli? or is there a portable device? Because of the times we are in i don't have huge amounts of money to lay out. But since my hearing is so challenged I want o get a good a hearing experience as possible. Thanks in advance. I am a professional musician.