USB or Optical output? which way to go on iMac ?

I just ordered a Mac Mini and I plan on using the optical out.  My music is stored on an external USB drive and I've occasionally had latency problems on the USB bus with both storage and digital out on USB.

Don’t think you can build a sound card into an iMac.

Toslink has an obvious benefit, both boxes are completely galvanic isolated.

It might be a bit high on jitter.

However, simple USB receivers can generate substantial jitter too.

As usual it is the implementation that count, not the protocol.

I am using the optical out on my iMac and it works just fine.  

Hi,

The notion of using a sound card with a Mac doesn't work because there are no slots to which you could use a sound card. I use a Mac Mini with a USB cable going to an external DAC. Both toslink and usb will work. For optimum sound quality, I would recommend USB. I use a USB cable from Locus Design. In my system and with my ears, the usb cable really does matter. Also, the playback software also matters a lot. I use Fidelia from Audiophile Engineering. If you are using a junk usb cable and using itunes, you are missing a lot of fun.

I personally think coaxial sounds better than optical and the latter sounds better than USB on the same DAC. Optical sounds less smoother and more digital to me. Its all a matter of preference of course. The closer it sounds to vinyl the better for me. 

I'd recommend an asynchronous USB converter like this (first cheap one in google); 

http://www.stereophile.com/content/musical-fidelity-v-link-usb-spdif-converter-0

I wouldn't worry too much unless you've got seriously high-end system. By then you'll be considering USB to S/PDIF converters costing hundreds of dollars. For what you've got now, just try each one and see if you notice any difference. You probably wont.

I agree with Currawong 100%.  It will also depend on if you are using hirez files.  You should familiarize yourself with the ins and outs of the USB part of your DAC, drivers, and what files it will accept.  If you are using FLAC/ALAC or MP3 files from CD rips, I doubt you will be able to tell a difference between your Toslink or USB implementation.  So I would default to whichever you happen to have the cable for.  Hi rez files, and a resolving system will probably favor the optical if the USB system in your DAC is basic.  I found this to be true on my office system using a PSAudio DigitalLink III (lvl IV mods).  iMac - USB < -optical < - Halide Bridge which is still in my office system.

As your system improves over time, a "basic" USB system (one that does not need drivers and only does 16/44 or 48) will be bettered by Toslink, and much more so by one of the nice USB converters discussed above.  Of course "system improvements" may involve another DAC with improved USB circuitry.