Hi, I just bought and installed an entry level TCL 55S425. I'm using an old Pioneer vsx1018ahk amp able to decode most digital input signals but newer Dolby Atmos. It is not ARC compatible but the CEC feature works. I just bought a cheap 25' Toslink optical cable to output sound from the Tv to the amp. I know that 25' toslink is a bit too long but it works. It only allows stereo with tv settings on auto and if I force settings to Dolby digital plus and DTS, it shows Dolby digital EX on the amp display with the 5.1 diagram. Sound is well amplified with bass Chanel active BUT sound is really only 2.1. Does anybody have a clue about this issue? I Read on another post that using the HDMI 1 (ARC) input could interfere with the Toslink output so I don't use it. Only HDMI 2 & 3 are used for a computer and a Chromecast/PS3 thru the amp.