Hey guys! I am in the market for a better transport for my audio. I use my macbook pro for my music listening. It has an optical output as well as USB connection (duh). I am looking for a DAC for around 150 or less that will enhance my listening pleasures.
It would be nice if it had a tube output stage, but good solid state would be good too. Any recommendation?

Finding a DAC at that price is not impossible, but you need to factor in the postage on top of it. The optical ones I can think of are the Zero DAC and the Beresford TC-7510. The Keces 131 has USB.

Trend Audio has one for $110 that has received good reviews.

The BlueCircle "Thingee" is within your price range as well.