The OP's argument is fallacious. He (she?) says that he could not hear the difference between three very low-end DACs, through low-end headphones. Therefore, ALL DACs sound the same. A 7 year old could tell you this makes no sense. The OP also has no knowledge of how to design or engineer a DAC. If digital to analog conversion is so easy, then I'm sure anybody can design and build one, right? Saying they are all the same because they "only" convert digital to analog is like saying all motorcycle engines of one liter have exactly the same performance. After all, they do the same thing, right? Just convert gasoline into torque.
I certainly wish all digital sources sounded the same. That would save me money. But they don't. Granted, all good digital sources will sound very similar. It will probably be impossible to tell two quality $1000 DACs apart in a blind test. But there are audible differences between something like an ipod and a Benchmark DAC. If there weren't, every recording studio would have a $100 external sound card and call it a day.
This "all digital sounds the same" nonsense is based on wishful thinking, not a knowledge of how these products are designed and how they function. Unfortunately, we don't have reliable, large-scale DBT tests of anything in audio, let alone DACs. The Wilson experiment is interesting, but anecdotal. It's not scientific in any way. So, I have no hard evidence to prove my point. I only have my own listening experience (not worth much) and the experience of thousands of recording/mastering studios who buy well-engineered DACs instead of a Wal-Mart DVD player. It *could* be possible that EVERY company that builds DACs over $50 is selling pure snakeoil, like the cable industry. But unlike cables, DACs cannot be built in ten minutes by anybody. Their design and operation is complicated. Given my listening experience and the available evidence, I find it extremely unlikely that every single DAC sounds the same.
Edited by tvrboy - 7/1/11 at 12:54am