About the Audio EDID switch
PASS:It means HDMI in and HDMI video+SPDIF and 2RCA (L/R) audio simultaneous output
2CH Mode: It means HDMI in to HDMI out and 2RCA out.It can extract digital 2CH PCM stereo audio signal from the HDMI input and convert it to 2CH analog stereo output through its RCA style L/R analog output. The RCA L/R output will not have sound if the incoming audio is multi-channel audio (>2CH). Set EDID switch to 2CH for RCA L/T stereo application.
5.1CH:It means HDMI in to HDMI out and SPDIF out.The SPDIF optical audio output supports all audio formats upto 5.1CH Dolby Digital 5.1CH / AC3 & DTS 5.1CH audio. But not support Dolby Digital Plus and higher formats,such as HD audio (Dolby TrueHD, DTS-HD Master Audio, PCM5.1 and beyond).