Macbook vs Squeezebox 3

The converter is where the clocks are, so it is very important.
Be sure to use the Vlink 192, not the Vlink in the black box or the Vlink MkII. The Vlink 192 has better clocks than the previous Vlink versions, and audio advisor has them on for $199. There are much better converters out there, but you'd have to spend at least an additional $250 IMHO.
Steve did not mention; the USB cable from the computer to the Vlink is also very important, as well as the digtial cable from the Vlink to the DAC. Most folks seem to think digital coax sounds better than optical, just FYI.
Why migrate away from the SB3 if it sounds so good? Because it has been obsolete'd by Logitech, i.e. no support?

Why migrate away from the SB3 if it sounds so good? Because it has been obsolete'd by Logitech, i.e. no support?

Exactly.

The V-Link came today. I just finished playing with it, for the last hour or so. Using optical wasn't much better than optical straight out of the Mac. However, once I switched to spdif, things came to life. Finally! Pretty darn close to the SB3, without any tweaking at all. This is on my regular Macbook, using a regular USB cable, iTunes and Pure Music. I now feel confident that I can go to a Mac Mini optimized for music, without compromising sound quality and possibly improving sound quality.

If you are using a stock usb cable, i can heartily recommend the pangea pc usb cable from audio advisor. It's $35 for a 1.5 meter length and the difference between this and a regular usb is very noticeable, i have the same dac, and i auditioned the pangea against stock usb and the audioquest forest, and the pangea gives a lot more clarity and detail. Which vlink did you buy?

I got a demo V-Link II from Crutchfield for $109. But on your recommendation, I just ordered a V-Link 192 from Music Direct for $199 & free shipping. I'll compare them and see if I can hear a difference, then return one of them. Once I get use to this setup, I'll try a couple of USB cables also. My digital cable is an Acoustic Zen Silver Bytes. I also just downloaded the free "Musical Fidelity" version of Amarra. I'll compare it to Pure Music and see if I can hear a difference there.

Thanks for your input.

I am actually in the market *right now* for a USB cable upgrade, and this is my short list, in case you're interested:
Kimber USB and USB AG
Audioquest Carbon
DH Labs USB cable
LAT International USB cable
Cardas USB Clear
Wireworld silver starlight
Ridge Street Audio Poiema
...still gathering information, also looking at digital cable upgrade, will add Acoustic Zen Silver Bytes...