PS Audio DAC output

Missak, glad to hear my second response was the correct one.  I followed the link but the writeup seemed like a sloppy translation from Japanese so I couldn’t make a lot of sense of it.  I’m not familiar at all with Sansui equipment so I can’t really offer help on that. Not sure what speakers you are using, but I still think the issue is with something other than the DL III.  Too many unknowns for me to offer any help, sorry.

I think I figured it out. I changed the sampling rate from 96khz to 192khz and the sound became smooth and "liquid". Since it is now late at night, I have heard in very, very low volume, so tomorrow I will check in a comfortable level. Still, it seemed to make a good difference. I hope I'm not mistaken.

Dear, pmotz. Do not worry, I appreciate your help. If you want to look at the schematic, the service manual is here: https://www.hifiengine.com/manual_library/sansui/au-a707mr.shtml

My (adorable) speakers are Harbeth Super HL5 Plus.

Solved! The problem was in AC power...

Fixed and sounding fantastic now. Running Squeezebox Touch as transport > Oyaide coax cable > PS Audio DLIII DAC. Smooth, full, articulated, zero fatigue. Goosebumps! Just amazing. Thanks.

The USB input on the DLIII is the weak link. I used a USB?SPDIF converter with the one I owned.