Audio Delay on iMac USB vs. Digital Outputs?

From my iMac, to DAC, via USB, the audio signal is delayed approx. 3 seconds vs the digital output (TOSLINK®-to-Optical Mini Plug Digital Cable) to the same DAC.

I have an M2Tech HiFace plugged in the USB out from the iMac and to DAC using an S/PDIF cable.

Contacted M2Tech regarding the audio delay and their reply "HiFace can not delay the output of the sound signal. The problem must be found on the player or the computer configuration used."

If the issue is computer configuration, any suggestions to fix and remove delay?

Why is it a problem?
Most annoying problem is that I have two other systems at home and often run them all at once, from the same source. One out of sync system is not good.

Secondly, video/audio from the iMac are out of sync, basically unwatchable.

Despite the response form M2Tech, I've been informed elsewhere that this is a problem with OSX drivers and not an issue with Windows.
They know about the issue according to this article,,,,,

M2Tech’s Mac OS X driver for the HiFace introduces a fraction of a second of delay between the source and output, which means that when you’re watching film or TV video, lipsync will be lost, with voices playing behind the pictures.

The M2Tech HiFace's designer Marco Manunta explained that the Mac driver works differently than the Windows driver: the Mac version doesn't work with fixed-size packets, so a large buffer is needed to avoid 'flux distruption' when several small data packets are sent, instead of one regular size packet.

Thanks for that info. Wish I knew that before purchasing the HiFace. I can tell you that the delay is greater than a fraction of a second! I'll send the link to customer service adviser at M2Tech.

Too bad as the HiFace is a very nice device.

I wonder if the delay would be there if you were running Windows on your iMac? I would think not but I guess you would have to try it. I have Windows 7 and Parallels running at the same time as Lion on my Mac Mini and it works very well. When you plug in a USB device it asks if you want it to be hooked up to Windows or Lion or both.

I bought a used copy of Parallels on Amazon for around $50 and you would need a full (not upgrade) copy of Windows.

I assume that if you are running Windows, it would require the Windows drivers, in which case it should perform w/o lip sync issues.
Installing Windows on my iMac is probably not something I will do.

Why not? You're not an Apple snob are you :>)

It runs seamlessly. I had my doubts too but once it boots up it's as if it were one operating system. No lags, no delays, no glitches, no crashes, pretty cool.

For video I just use one of the tradition digital connections. In this case, the optical out of my Mac Mini or SPDIF out of my BR player.
Herman -- No Apple snob!:)

Installing Windows may be something to look into after doing a little research. Not sure I would do specifically to use the HiFace.