Macbook to USB to which one?

If you plan to use USB you will be limited to 16/48 files with both the MF VDAC and the DACmagic. One thing to point out is that the DACmagic has high levels of jitter when using USB. The MF VDAC by contrast has impressively low levels of jitter when using USB as reported by Stereophile. If your primary use is going to be USB and you will be using standard 16/44.1 I would go with the VDAC over the other options, added flexibility of additional inputs over the HRT and better USB performance compared to the DACmagic.

Bwp,
Thank you! That is exactly what I needed to know.

Doesn't the Macbook have the headphone out which is also a digital output? You can buy a simple plug that converts the headphone out to toslink. Then you don't limit yourself to USB DACs, which really takes the better DACs out of contention. I would double check your manual to see if the headphone out also doubles as a digital out. I have three mac laptops in my house (mine, son and daughter) and all of them have the digital headphone outs. Two of them are already 18 months old.

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.