ALSA devices

[Halz79]

I'M using a Topping E30 with Jriver IDPi (rpi4b).  I'M trying to understand the differences between the the numerous E30 alsa devices. I mostly use "HW", but occasionally A-B with the other options ( plughw , iec958, ..). With the usb regen in the chain there is not much difference. When I remove the regen, "HW" is the best sounding. That led me to believe that HW is the asynchronous mode, the other options use the Pi clock. I guess when the regen is used, it reclocks the pi usb, which is why it sounded the same as HW. Am I totally off base with my assumptions? Can't really find info of what the differences are other that HW does not go through any software conversion. I ended up liking HW without the regen best. Anybody?

[Miska]

All these cases handle hardware the same way, but they are different from the software stack point of view.

 

"hw" is the direct no-conversion access from application to the device driver. "plughw" is similar, but can do simple word length conversions and such between application and the driver, and allows routing plugins. 

 

iec958 is mostly related to S/PDIF for passing raw data, typically used for Dolby Digital or dts.