Headphone amp/dac connection

Just picked up a nice little Ray Samuels 'The Predator' portable amp/dac today.  Now just need a cord.  Anyone care to comment on the best way to go?  The amp has USB micro on the back and 1/8" input on the front.  I will be coming out of my MacBook Air on the desk top primarily.  USB to micro USB best?  Or just go 1/8" headphone jack on the Mac out to the 1/8" input?