I have tried both as well as some other devices, the order in which I would put them in terms of sound quality are
- Mac/USB/VLink/Naim DAC
- Mac/Firewire/INT 202/Naim DAC
- Mac/USB/HiFace/Naim DAC
- Mac/Optical/Naim DAC
I found 1), 2) and 3) all sounded better than 4).
Overall the one, I liked best was 1) and that is what I use, moreover I found no noticeable difference switching between an optical and coaxial cable with the VLink in place. On my Sonus, which I use to stream music to my Naim DAC, I prefer the coaxial.
The results might be different with a different DAC because the Naim design is quite unique. However, I was only interested in the Naim DAC. The only other DAC I've had was from Chord - the entry level GEM - an excellent product, but not as musical to my ears as Naim - plus it had no S/PDIF input, but a very interesting Bluetooth interface, which outperformed its USB, but still fell short of the Naim DAC and indeed the Naim UQ.
I have also tried
- PowerMac/VLink/Naim UQ
- PowerMac/Optical/Naim UQ
Here the difference was less pronounced (not what I expected), but I still had a slight preference for 1). I think the PowerMac has a better optical out than the MacBook - it is on its sound module and does not double as headphone socket.
So I think the hiFace will give you better results than the optical out on your Macbook, but I've no experience of Bryston products - so cannot be sure. In any case it is only my view and others may have different views.
Best results I've heard through a Naim DAC were using the CDX2 as a transport and better still my humble Cable Star Transport - the CST cost me £3.45 and plugs in to the rear USB port of the Naim DAC making it easy for me to play USB sticks. However, can't say I use it that much - it so easy to just hit an album on the Sonus.
All the best, Guy