I don’t know what the wooden tube does, but I concur with @bolivarjoy, I had a dedicated line from the panel with true earth ground rod and hospital grade pure copper AC outlets installed. Digital source, 20 wpc 300b/845 SET tube amp and high sensitivity Klipsch Forte speakers. The dedicated line dropped the noise floor to the floor! Also powers the router, dedicated switch box, and LP supplies.
I could always hear transformer hum through the speakers in between tracks or with quiet passages. Tried DC filters, USB filters, lower gain signal tubes, and even minus 10dB attenuation, still hum. Worse some days than others, quietist late at night. Once the dedicated line installed, transformer hum virtually gone, I no longer can hear from seat.
Second best upgrade was a DDC between a fanless mini PC streaming source and the DAC, darker background, larger soundstage and way better stereo images. Together with dedicated line, I might actually be done…with this system anyway. Have four others I can tinker with. 