Macbook to USB to which one?

After a lot of research, I hooked up my MacBook Pro to a Wavelength Proton DAC and never looked back - sound is excellent. Main reason for selecting was the performance with a USB connection.

I bought a Centrance DACport a few weeks ago to use as a portable USB DAC + headphone amp for my MacBook. The thing is TINY, but the DAC is really really good. I also now use it in the office to play my computer tracks through my speakers (Rotel separates + Meadowlark Kestrel Hot Rods) and am amazed at how good it sounds - esp. with high-res tracks or high bit-rate internet radio like the Linn stations.

Centrance also just began selling the DACmini, which doubles as a headphone amp (and pre-amp, I think), but it's more money (http://centrance.com/products/dacmini/)

According to Stereophile, Centrance licenses its jitter-reducing technology to Benchmark, Lavry, Bel Canto, Empirical Audio, and PS Audio, among others. Well worth a try.

I'm getting outstanding results using iTunes > MacBook > USB output > Ayre QB 9 > balanced out to my integrated amp. Very basic, with excellent results. The only sound I hear is from my speakers.

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.