Im designing a multi room AV system with distributed video. The system will be accessed by the user by a control system.

Most of the TV zones will just use the TV speakers, most of the HDMI sources are in the rack and the distribution will be handled by a HDbaseT matrix. All pretty straight forward.

The problem comes in the cinema room, which is a 5.2 system.
At the rack we have the Cinema Room AVR (Denon 4800H), Sub Amp, Apple TV, Cable Box, HDbaseT matrix, etc.

In the Cinema Room we have 98" TV Samsung TV, Surround Speakers, Subwoofers, PS5, Bluray Player.

Where video sources are in the rack its easy to pass them through the matrix, then out of the matrix via HDMI into the AVR, out of the AVR via an HDbaseT balun to the Cinema Room.

Where video sources are local to the Cinema room already eg. PS5 and Bluray player, im unsure as to the best way to get the audio back to the AVR in the rack.

My thoughts are as follows, but please let me know yours :

Option 1 :
Local hdmi source connected to TV, optical audio out of TV, brought back to Rack via Optical Audio Return (Toslink) port on the HDbaseT balun.

Potential Issues / Limitations :

• Lip Sync - the TV will receive the video and audio quite quickly, but then the audio has to do another lap back to the AVR.
• Toslink has bandwidth issues.

Option 2 :
Route the local HDMI sources back to the rack over an HDbaseT balun, once at the rack put the video + audio into the AVR, then back out of the AVR via HDbaseT back to the cinema room.

Potential Issues / Limitations :

• Seems overly complicated, with too many points of failure
• Will need multiple HDbaseT balun pairs. Eg. 1) AVR to TV, 2) PS5 to AVR, 3) Bluray to AVR 
• Potential lag for games. (HDbaseT is meant to be lagless, but in reality nothing is so not sure if this will work)

Option 3 :
Use eARC via the AVR to TV HDbaseT balun.

Potential Issues / Limitations :

• eARC requires CEC to be enabled and CEC causes all kind of issues so we always disable it. One work around would be to use a CEC blocking dongle on the TV and ARV. I understand the dongles work by disabling the CEC pin on the HDMI connector, but still allow the eARC pins to work. Such dongles are available from Amazon and / or Lindy. But ive never tried this.

Option 4 :
- Run 3x 20m Armoured Optical HDMI 8k cables from AVR to TV location
- Run 3x 20m Armoured Optical Optical HDMI 8k cables from local device location to AVR
(quantities allows for spares)
Further consideration :

• At this stage we will only be using maximum 4k 4:4:4 60 so the cable gives allot of headroom
• HDMI cables can be fragile. The rack is on wheels to allow it to move for maintainace, the cables will be in a sock together with other cables to mitigate strain. The HDMI cables are armoured to mitigate damage. 
• The Optical HDMI cables required for 20m runs have small chips in the connector head which can die.

Option 5 :
- Place the AVR local to the cinema room / local devices (eg. not at the rack end). This is a good idea, but there is no room unfortunatley.

What sort of length on the wire between the main rack and your cinema?

back in the day i would just take the local sources back to the rack and into the distribution system. that way all av traffic went to matrix first then to the room in question.

20m, i think i know what you are thinking... Ive just edited the question to add option 4.

option 4

I vote 4 or 5. I use the Cleerline HDMI cables, up to 40m, and they are actually pretty robust as long as you do not bend them really hard. From the wall to a rolling rack in a wire bundle will be fine.

Why not option 2 with an HDMI switch at the local sources so you only require 1 HDBT transmitter?

Obviously option 4 would be the best fail safe option which provides you endless flexibility however the price of 7 optical HDMI cables seems extreme

I did consider a local HDMI switch, but discounted it as an additional point of failure

I costed out the HDMI cables against a eARC HDBaseT switch the cost wasnt as bad as you might think. c. £450 for 6x 8k 20m HDMI vs c. £400 eARC balun pair (multiply by c. 1.25 for USD)

I’d find a way to have the AVR local and then use a single optical HDMI back to your matrix. I’d highly recommend to at least pull an additional 1 or 2 as a backup, plus your standard amount of CAT6A/7 cables.

Least amount of failure points, with future capability. Hell, throw in a 6 strand of OM4 fiber too, while you’re at it.

Hell, throw in a 6 strand of OM4 fiber too, while you’re at it.

AVProEdge HDMI cables are made of Cleerline fiber so in the future, you can cut the head off and use the fiber for anything.

So in other words, AVPro cables are rebadged Cleerline cables. Noted.