I swear this worked for me before a couple weeks ago. I recall that in the AiOS, I switched the Audio settings for HDMI from RAW to LPCM and LPCM-Multi Channel to try and prevent the subwoofer from popping when I pause/un-pause 5.1 channel content. I went straight back to RAW when I realized 2 channel sourced content had no subwoofer.
Source: 2 channel .flac music files (well, ANY 2 channel source; audio or video)
Player: Pivos AiOS media extender
Receiver: TX-NR509
Listening Mode: Direct
Speaker config: Mains = small, Subwoofer = yes
When I begin playback on a 2 channel source, I get L+R, no subwoofer. This is different than a couple weeks ago when any 2 channel source would kick out sound through the mains AND subwoofer.
I hope someone can help me get the lows back...
