WiiM Ultra line out vs. optical to KEF LSX II — why does double conversion sound better?

[huyvoxyz]

I’m currently running a Wiim Ultra into KEF LSX II speakers. Previously I used optical out (with fixed volume) to keep the signal digital and ensure bit-perfect transmission to the KEFs.

Today, I decided to test the line out to the KEF aux in. On the WiiM, I selected the "Corrected Minimum Phase Fast Roll-off" DAC filter. To my surprise, I found the sound subjectively improved and much preferred it over the optical connection.

Here is where I am confused: I know the KEF LSX II uses an internal ADC to digitize all analog inputs for DSP processing. Theoretically, using line out creates a redundant conversion chain (WiiM DAC -> analog -> KEF ADC) and is no longer bit-perfect.

Why does the "messier" double-conversion chain sound better than the direct digital link? Is the WiiM's DAC just that good and it can outweigh the theoretical loss of transparency?

 

[hgo58]

I’m currently running a Wiim Ultra into KEF LSX II speakers. Previously I used optical out (with fixed volume) to keep the signal digital and ensure bit-perfect transmission to the KEFs.

Today, I decided to test the line out to the KEF aux in. On the WiiM, I selected the "Corrected Minimum Phase Fast Roll-off" DAC filter. To my surprise, I found the sound subjectively improved and much preferred it over the optical connection.

Here is where I am confused: I know the KEF LSX II uses an internal ADC to digitize all analog inputs for DSP processing. Theoretically, using line out creates a redundant conversion chain (WiiM DAC -> analog -> KEF ADC) and is no longer bit-perfect.

Why does the "messier" double-conversion chain sound better than the direct digital link? Is the WiiM's DAC just that good and it can outweigh the theoretical loss of transparency?

This double conversation may add a bit of distortion and filtering to the audio. Many people prefer this, as it often sounds more warm. It's the same reason that some people prefer tube amplifiers, as they have a high amount of distortion compared to a pure transistor based Amp.

I cannot say if this is the reason you like it better but it could be.

 

[rccarguy]

maybe the conversion cuts a bit off the top end of those speakers, which do have a bit of marmite sound to them.