Hi Ted and thanks for stating what I have held to be true for quite some time. "version of actual DAC chip seems less important". Don't get me wrong, you need to use a good chip. However, there are great chips from Burr Brown, AKM, Wolfsen and ESS SABRE that all sound great.
BUT, if you have excessive jitter and couple to an inferior analog stage, the sound will NOT be good. I would expect the DAC that has the poorest specs on a list of DACs, with correct clocking implementation and a good analog stage will EASILY outperform the superior DACs.
When we finalize the design for our own DAC, I will choose the DAC chip carefully as well! But, everything matters and I do believe that too much importance is placed on the actual DAC chip, without an understanding of the REST of the circuitry that is needed to make the end product perform at its best.
Obviously, adding a digital input to the Sony or Oppo players allows the use of their DACs, which are Burr Brown and ESS SABRE, respectively. Both excellent DACs. The mofied units have our tube analog stage which is also exceptional, with a very sophisticated tube-rectified and dual-discrete SS voltage regulation circuit. If we are to add a digital input to the player then, the key is HOW the data is interfaced to the DAC, in such a way that jitter is minimized, all other things being equal. This is why I REALLY WANT to pursue the option with a proprietary and sophisticated clocking system - beyond that of a simply crystal oscillator with voltage amplifier - that includes buffering and algorithms that produce the absolute lowest jitter I2S digital signal (native data format) to the DAC.
I am about the pull the trigger here, but I need to know that there is sufficient interest, as the standard method of using a simple input receiver with crystal will be good, but not GREAT. I want this solution to be GREAT.
This digital input and clocking circuit will also be used then, in the DAC that we design for our standalone product in the future.