I am very confused by ASR loving these cheap DACs. My Yiggy has a very large PS and sounds great. My interest is curiosity as to how these $300 to $600 dacs test so well and have very low noise.
@koestner, it is understandable when all the people commenting are telling you that this level of performance must be impossible the way they are designed. However, all these replies telling you that have one thing in common. They are all made by people who are not EEs, and who lack any significant amount of electronics design experience. What they are telling you comes from product marketing sheets, not from real world knowledge and experience designing these types of products or similar types of electronics products.
@holmz , no the AP does not have a crazy high input impedance. A few minutes of Google would have shown it to have 100K resistor in parallel with 100pF, or very close to most pre-amps and amps that we would use. It also has selectable 600/300R termination.
@koestner , the units were measured and achieved the performance measured. That cannot be explained away any more than the units that were measured and measured poorly obtained that level of performance. All the excuses in the world does not change that.
Where I personally would be concerned about the performance I may achieve in my system would be with USB on the lowest cost units due to the lack of isolation. This could result in ground related noise from the DAC connected and the next device in the audio chain. If this is the case, though, you will hear that noise in the quiet passages of the music. If you don't, draw your own conclusions. Audiophiles like to repeat phantom, effectively non-audible noise sources they read about on data sheets. A few minutes on Google and you will find USB isolation products for a few hundred dollars.
Below are pictures of two well respected DACs even within this community. One uses a simple 12V external wall wart. One uses an internal, what looks like an off the shelf switching power supply. In both, all internal voltages are generated on board. If you look at the second one, the layout is pretty tight. Other than the enclosed power supply (metal case adds a few dollars to cost at most), there are no fancy shields, no special compartments for each section, No esoteric capacitors or resistors. However, while many audiophiles do not like its sound or more specifically its lack of sound, no one seems to question the validity of the performance it achieves.
This is a $300 product. It has less features. It does not have many big electrolytic capacitors, but it has lots of tantalum capacitors (rectangular yellow things) which many other boards do not. Properly used they can fulfill similar functions. If you look at the DAC sections, they are not all that different. Their higher end product which achieves even better performance and has more features does have more complexity and obvious power components, but does not squeeze that much more performance out.