APL wrote:
"Yes you are using Op Amps for I/V conversion, but the Berkeley example has them all the way, from DAC chip to output."
Op-amps are far from perfect, even though the textbooks would lead you to believe it. However, like most things, the answer is "it depends". It depends on how the power for the op-amp is treated and what op-amp you are using. I have done a lot of experimenting with op-amps in the past and learned a lot of things that are not in the textbooks. If you choose the right one and treat it properly in the design, it can be just as good as a discrete circuit and sometimes better because the layout of most discrete circuits does not allow for optimum power delivery. The compact nature of chips allows for optimum power delivery.
"Further more, claiming that S/PDIF is best as well as DSD to PCM conversion (even done by a computer) is way out of line, at least in my experience. "
I never claimed that S/PDIF is the best method for DAC input, but again the answer is "it depends". If the circuit is well-designed, a good coax cable is used and the right receiver chip is used, it can be every bit as good as the best internal USB interface. So close that no one can pick it out in A/B comparison. I have done this.
Steve N.
Empirical Audio