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USB to S/PDIF: Trouble in Paradise

My reference DAC is an Alpha from Berkeley Audio Designs. This is a great DAC, but I have a problem: my “transport” is a computer, not a CD player. So, I need some way to get the bits off of my computer and into the DAC. Making things complicated, my computer is an 8-year old Apple Power Mac G5.

I suppose I could get a new computer, but while that’d open up the most avenues, it’s also the most expensive. By a lot. A new Mac Mini (good) would run to a grand, an iMac (better) would be over twice that, and a Power Mac tower (best) would be 5x. So, for now, at least while Old Mac is hanging on, I need another (cheaper) option.

One way to do this is to run an optical cable from the Mac to the DAC. The problem is that this is generally not a great way to go — S/PDIF over Toslink isn’t usually the interface considered to be the highest in performance. I’ll leave aside why for now because the question of performance is moot; the optical out on my Mac only supports 16bit/44.1kHz sampling, and I want hi-res (24/192). So, optical is out.

Given that my DAC only has two other kinds of inputs, one BNC and one AES, and also given that my computer has neither of those, I’ll need some kind of external converter or an internal PC card. With regard to the latter, a Lynx card does support 24/192 output over AES, and is even recommend by Berkeley as the “transport of choice”, but I’ve heard one of those get gobsmacked by an external USB-to-S/PDIF converter that I actually own, a Legato by Analog Research Technologies. The Legato is very well built and sports a superstar list of specs, but it’s a Redbook-only converter (16/44), so while it’s awesome, it isn’t my Final Solution.

Ok, so I need a hi-res capable converter that can take a connection from my computer and translate it into something my DAC can handle; either USB or Firewire should work fine.


I’m sure there are and will be more, but those are the ones coming to mind.

Offhand, I have to dismiss all the ones that rely upon the native Mac OS 10.6.4 drivers for USB Class 2 audio (which is the only one that supports 24/192). Why? Well, because my Mac uses a PPC CPU, not an Intel, so there is no support on my machine for 10.6 — I top out at 10.5. This means that (AFAIK) the Wavelength, the new Sonicweld, the still TBA Berkeley, and the Audiophileo are all out of the running. This leaves the M2Tech, the Weiss, and the PS Audio.

Of the three, the Weiss is probably the performance fav, but at almost $2k, it had better be as the price is ludicrous. Adding that price to the cost of the Alpha, it’s just not clear why I wouldn’t just get an all-new DAC that has a more computer-friendly interface, such as a Weiss DAC202. While I’m sure that DAC is just superlative as well, and some say that it’s even better than my Alpha, I’m not convinced I need to spend that much to get where I want to be. And yes, there are DACs that do very well with a Firewire interface, such as those made by Metric Halo. But while those products have their fans, I find it hard to be one of them. Still, it’s an option to consider.

The PS Audio looks to be the most flexible approach — I can run just about anything I want into it, however I want — but then, it’s all a bit fuzzy since the product hasn’t been released. More details should be forthcoming in a few months if they hold to their announced release target (Jan), but if they don’t, well, God only knows when we’ll have more to talk about.

Which leaves the Evo. Not sure that there’s any other serious choices for both hi-res and support for an old Power Mac. Looks like I’m going to have get one of these and report back on my findings. I’m nervous as some preliminary reports on the Evo on ComputerAudiophile aren’t particularly overwhelming, but I suppose we’ll have to see.

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About Scot Hull (975 Articles)
Founder, Editor and Publisher at Part-Time Audiophile and The Occasional Magazine.

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