Maybe this topic has been discussed in some form before but I would like to see If I can get a definitive answer. My setup now is Arc + Sub + Era  300.  My Tv is a LG CX with passthrough enabled. 

So I just upgraded my Play:1 to Era 300 for surround sound. My main playback device is an ATV 4K with Infuse for playing back my Blu-ray rips. This all works great except ofcourse for Dolby TrueHD Atmos because the ATV 4K will convert everyyhing to LPCM. This is the reason I bought a Zidoo Z9X Pro with passthrough for movies with Dolby TrueHD Atmos. This also works great and the Era 300's sound amazing. 

So I was doing some testing with some Dolby TrueHD files (No Atmos! This is important) and I noticed that the Zidoo with passthrough is much louder than the ATV 4K + Infuse that outputs LPCM 7.1. Reduce loud sounds is off.  I know that in theory the LPCM stream should be identical to the TrueHD stream (just uncompressed).  Any ideas on how this is possible. Does the ATV 4K just have lower output or is that not possible? It is not a real problem, I can ofcourse increase volume when using ATV.