DAC discussions

[RPI4 Rambler]

lol, OT for sure but...

The Pi Audiophile space has moved well beyond the noisy stock Pi's, cheap power supplies and HAT's. The Allo USBridge SIG, an OEM grade platform, + Allo Shanti LPS is a super low noise, clean power system for driving a well designed, Native DSD capable DAC.

Linux and it's single, universal USB audio driver and quirks config supports many native DSD capable DACs.

Here's some screenies of native DSD out to an Allo Rev DAC. The files are DSF64 and 128 format but the DAC also supports 512 . I personally don't do much with DSD other that to test that DoP and native work with moOde.

 

Now, even more off topic!
Nice stuff for sure, the USBridge SIG alone is $ 240. The Shanti another $ 160. Add the RPI, case etc. Pricewise you could probably purchase a streamer such as the Onkyo NS-6170, now a few years old, but with functionality far exceeding anything available on the (user attainable) RPI platform, such as a digital radio receiver (in Europe DAB+), a dual differential DAC implementation (AK4490 no less) etc. I've heard it's not available in the US, but surely comparable ones are available. 

Look here http://archimago.blogspot.com/2018/12/me...-b-as.html for noise/distortion etc. measurements of a relative simple RPI3 system, including a simple switching power supply and a battery (one of those power banks). Recently, the author carried out an upgrade to that system. 

It only proves that the RPI3B was already suited to audiophile application, and it took Allo quite some time (relative to the speed of developments in the digital domain) to come out with equipment as sophisticated as yours. The Aoide Hat retails for around $ 50. 

As to "native DSD", many DAC's that supposedly support "native DSD" do not take the "DSD Direct" route. So the native DSD signals pass the PCM route, with all kinds of processing 'goodies' instead of bypassing it. It's a design choice made by the DAC designer. The most blatant is the conversion to PCM, following its path, and finally, reconverted to DSD. By its very nature, there's very little one can do with a DSD stream in the digital domain; for instance simple digital volume control or plain editing to change something in the song. The moral: "native DSD" is only "native" if it's also "Digital direct" (so straight to the analog conversion stage).

It's actually very clear when one studies the functional block diagrams of the DAC chips that every manufacturer publishes, with the exception of ESS; their interpretation of functional block diagrams are laughable. The implementation of the DAC chip decides whether or not the Digital Direct mode is available. 

And don't even get me started on "power supply cleaners", "USB cleaners" or "jitter killers". Objective measurements reveal that they are ineffective (a nice way to avoid the word 'bogus'). In several cases they make matters worse, not better. Now the RPI's are targeted too. 

Alright, enough already with the off-topic stuff!

The original problem still exists, but I will continue searching for a solution.

Cheers,
marco