Macbook to USB to which one?

FWIW I use the M2Tech Hiface to convert USB to SPDIF. I'm no techno man but for reasons unknown to me it works wonders! Note: I go from an iMac to a Krell processor. The M2 Tech is the best "go between" that I am aware of.

I've been using a Dacport for about 4 months now, not with a Mac but with an expensive Lenovo laptop. I use if for many hours a day. Originally I used it just with my Denon 5000 headphones when I was out working, but then after talking to Michael Goodman, the head of Centrance, I tried hooking the Dacport directly from my computer (playing only AIFF files and Itunes) to my home amp via a simple 1/4" to RCA adapter and the results are stunning: much more detail than I heard through an NAD CD player playing the same song, be it rock, classic, etc. Another great thing about Dacport is that Michael Goodman answers phone calls and emails. The unit is super strong and also doubles as a Class A headphone amp. To pay only $400 for a DAC that has this many uses is quite astonishing. I plan on using it to run from my laptop direct to my Bryston 4B-STT2 and then my Mag 3.7's. I'll post the results. Goodman told me that the chip in the Dacport is even more advanced than the chip in the Benchmark DAC which goes for close to $2,000.

After 2 months of listening, I have to say that the Centrance DACport is one of the most satisfying bargains I've ever purchased in audio. I keep it in my headphone case when I travel or work at the coffee shop, and hook it up to the office system when I'm there. I love the fact that it doesn't need a power cord but still has ample power to drive my Sennheisers and Audio Technicas. I'm not saying it's the best DAC or best headphone amp you can get, but it's super convenient and a downright steal.