[EliasGwinn]

Originally Posted by audioengr

That's funny. I see how you made the measurement and it makes sense. I also use the TAS1020 in my products and I definitely hear a degrading difference when using the Windows drivers on XP rather than a custom driver. In fact, I also hear a difference when I bypass KMIXER. The driver makes a bigger difference in my case though.

Steve N.

Although I wouldn't dispute what your ears tell you, we found that digital audio data could be streamed bit-for-bit perfectly through kmixer when using usbaudio.sys. As mentioned before, this was proven using a digital audio bit stream with a known bit sequence, and it was found to be identical coming out as it was going in. Aside from the bit-test, we also measured the audio performance (Freq response, THD, IMD, etc) of this setup, and it was completely similar to the all other digital inputs of the DAC1 up to 96/24. The third test was listening. I am still conducting that test as we speak, as are several others here at Benchmark. With a CD transport feeding the Coax input, and the computer feeding the USB with the same music, no one has been able to differentiate the two inputs.

With that being said, there are several things that can affect your audio within a computer besides simply going through kmixer. However, we have found that when everything is configured properly, the digital audio can be streamed transparently through kmixer.

We will be publishing an online Wiki that will document everything we have found with various media players, OS's, etc.

Also, with all due respect, the Windows driver is only one aspect of the streaming technology. I am not familiar with your product, but the firmware for the TAS1020B is the main difference between our solution and others on the market. The majority of the development time of this product was spent programming the firmware for that chip. It is a completely custom solution designed to handle streaming USB audio gracefully.