Excessive Gain in PCM Stereo/Spotify over HDMI - Feature Request for Native fix (Bit-Perfect mode)

Hi everyone,

I am using the new Zidoo Z9X 8K generation connected to a Marantz SR7012 AVR, with a highly calibrated dual subwoofer system running OCA's Evo Acoustix target curve.

When playing multichannel cinema formats (Dolby Atmos, DTS-HD MA) via RAW/Passthrough, the sound quality is pristine, perfectly balanced, and powerful. However, I am experiencing a significant acoustic issue when playing stereo PCM content, specifically when using Spotify or streaming stereo FLAC/MKA files through the native Music Player 8.0 over HDMI.

The stereo PCM output over HDMI sounds excessively loud, overly bright, and lacks dynamic control compared to other bit-perfect streamers or native HEOS playback on the Marantz. It feels as if the Android Audio Framework is applying an internal digital gain stabilization before sending the PCM signal down the HDMI pipe, causing slight overmodulation, jitter duresse, and high-frequency fatiguing brightness on highly resolving speaker systems.

To bypass this HDMI audio framework limitation, I tried using the Optical/Coaxial output for PCM while keeping HDMI for video (using the AVR's "Video Select" feature). While the audio quality immediately returns to being warm, sweet, and perfectly balanced over the digital cable, this workaround creates a major usability bottleneck. Switching between the Optical/Coaxial input for music and the full HDMI input for Dolby Atmos movies requires too many manual steps on the AVR remote, ruining the seamless experience of a premium home theater setup.

Since the Zidoo Z9X 8K hardware is incredibly capable, I would like to ask the community and the dev team:

1. Is there an hidden setting or a known trick to force a true, untouched "Bit-Perfect" digital line output for stereo PCM over HDMI, completely bypassing the Android OS master volume/gain stage?
2. Has anyone found a cleaner way to handle this dual-routing scenario without constantly changing the AVR's Input Assign or Video Select parameters?
3. Could we officially request a firmware update to include a feature like "Force Native Volume / Disable Android Gain for HDMI PCM" to ensure high-end stereo music gets the same unadulterated treatment as bitstream cinema passthrough?

I would love to hear if other audiophiles with calibrated rooms are noticing this PCM brightness over HDMI and how you are handling it.

Thank you in advance for your insights and support!

 

Is Audio/HDMI Setting/Volume passthrough mode: On ?

Is the marantz switching to a stereo upmixer? (Multi channel stereo, dts neo or such)

Replay gain off ? (Keep it of, it only works for pcm stereo)

 

Is Audio/HDMI Setting/Volume passthrough mode: On ?
Yes.

Is the marantz switching to a stereo upmixer? (Multi channel stereo, dts neo or such)
No. Marantz is playing exactly PCM 2.0

Replay gain off ? (Keep it of, it only works for pcm stereo)
No option for replay gain off, as far as I know in zido Z9X 8k (maybe yes in other models but not in Zidoo; only volume control which of course is also off)

As fas as I know everything is a android limitation in models with only one hdmi out. I think in models with a dedicated audio hdmi out this problem is resolved

 

I have the z3000 and has enough limitations even on the dedicated hdmi.
The MP is far from bug free.
As far as i know: only stereo is fully functional.
Can't explain what's happening on your zx9
.
Can you reconnect the hdmi during stereo playback . (As a desperate option to try)

 

Thanks for your reply. I am not sure if I follow you.... sorry
I try to explain a bit better. I have not problem at all with the zidoo for all the formats. The only problem (maybe is not really a big problem) is when I play stereo content (from a FLAC from my personal collection or from spotify (not connect, but from the app)). The zidoo converts the FLAC to PCM and I feel like is added a gain to the original source and I feel like the music lost some of the dynamics (is excessively loud and overly bright). Something that I cannot feel when I play the same source in HEOS connect (which send directly FLAC to the Marantz). I think the Android Audio framework from zidoo is applying an internal digital gain stabilitzation before send it to the Marantz (something that is not happennig when I play via HEOS).
No problem at all with DTS, ATMOS, DOLBY DIGITAL or any other encoder. Only I feel that with stereo content converted to PCM

 

I cannot comment on the android audio framework. But the guys at zidoo are no idiots. So i think they do not allow android to intervene.
but since i use the 2nd hdmi on my Z3000 i just don't know.

Is your output set to raw? Do hires flac stay hires? (click the status button on your marantz, it will inform if you get 44.1/48Khz or higher)

Flac is PCM (unless you put DTS into it, wich is multichannel masked as PCM) so there is (should be) no conversion. So if the zidoo is converting it's is because some settings tells it to convert.
Is your EDID manipulated? PCM should be a walk in the park for a zidoo, hdmi and a marantz.

My suggestion to rebuild the hdmi handshake during stereo is to force a stereo connection.

 

My configuration is:
Audio/Source Output: HDMI
Audio/HDMI Setting/Decode: Auto (no RAW option in the new model)
Audio/HDMI Setting/Volume passthrough mode: On
Audio/Pass-through compatible mode: On
On marantz the status is PCM (not FLAC).
No manipulated EDID

If I compare HEOS play and ZIDOO play of the same file/music local and also spotify, the ZIDOO adds some gain to the source with in my ears add a bit bass distorsion/a bit excessive bright sound
For you acknowledge, If I switch the audio to OPTICAL/COAXIAL (SDPIF), obviusly I cannot use DOLBY ATMOS, DTS:X...etc. but for STEREO sources I do not feel the added gain and not really appreciate any different in relation to HEOS play.
I really don't know the technical details regarding the android. I find the info in this thread: https://forum.zidoo.tv/index.php?threads/volume.94699/

 

Don't HEOS enabled AVRs have dynamic range restoration and other compression "undo" mechanisms? I know my Yamaha seems to have it enabled by default for streaming sources. That may explain the differences.

 

Yes and nope. My AVR is Marantz SR7012. It do have dynamic range restoration but it is OFF. Same config for HEOSs source and zidoo source.