D/A High voltage use R-L-C-L-C net to generate 230V for Tube 6922 plate-voltage.
Rectifier is 6Z4 and put in delay-on function.
D/A output OP +15/-15V power supply by switching power.
Spdif receiver is CS8416 and Codec is WM8741.
All circuit design usage SMT components.
Serial audio path usage DIP components for high Q factor issue.
The view of Audio signal switching and audio-input of tube.
D/A Top view picture.
Add 6922 heater R & C components.
Add Tub output OPT for good sound.