"Let me share a few things. In the first place DAC's are DAC's and ADC's are ADC's. They all produce results that are audibly the same if not digitally the same. Any audible differences would have to be engineered into an analog stage of the equipment. In other words, something would have to be done to the analog circuitry to modify the frequency response or add harmonic distortion (vacuum tubes) or something to make the audio stage of the equipment operate in a non-linear fashion. You can't change the "sound" in the converter chip itself."
FMW, thanks for your response. I understand about the non-linear modifications to the anologue circuitry that can be employed to make the device sound different. My question lies in the differences that people, at least, claim that they can hear due to the differences in analogue circuitry designed to be linear. An example would include different types of op-amps used, discrete designs versus ICs and a host of other topologies. Another claim is that the power supply makes a sonic difference. Yet another is modifications to the clock of the device. Below are exerpts from Black Lion's own website. Notice they do not agree with your statement that an ADC is an ADC and does not effect sound.
"(The un-modified Digi002) Line stages are based around ST Microelectronics' version of the TL072 and TL074, and JRC's NJM4580 and NJM5532. Personally, I find the TL07x family to be a little on the noisy side, and I don't care what the 4580's datasheets claim, they're NOT low noise either."
"While experimenting with clock designs, we found that we liked the quality of the audio better when the master clock frequency was increased. Due to the superior nature of third overtone XO crystal oscillators (they have inherently less jitter than fundamental XO oscillators), we decided to increase the 002's original master clock frequencies, and then divide them down as necessary. We started with a pair of ultra-low jitter (1 picosecond average) XO oscillators, one for 44.1 kHz and its multiples, and one for 48 kHz and its multiples. We divide these two frequencies using a proprietary method that keeps accumulated jitter to a bare minimum: under 10 picoseconds. Would you ever use the word "punch" when describing the sound of your 002? With our internal clock, you most certainly will."
"In late 2006, we began experimenting with linear power supplies in the 002. We've never been big fans of switch mode supplies in audio, mostly because of the way they seem to strip the audio of any real body or impact. By powering the analog and digital stages separately, we felt we could improve overall sonic character as well as completely eliminating the power supply as a source of crosstalk between analog and digital. By using a low-emission toroid with a bigger power supply rail, we are increasing headroom, and as a result, dramatically improving sonic impact."
"We also toyed with different converter configurations. Converters are very sensitive to their power sources, and proper decoupling is very crucial. We began to experiment with some theories concerning resonant frequencies within power supplies and their overall impact on conversion. After almost six months of testing, we came up with a proprietary method for reducing the noise and decoupling the 002's converters. We feel the end result represents a great breakthrough, and takes the 002 to a completely new level of sonic quality."