Introduction

Have you ever experienced this situation: when watching movies directly using the built-in Google system on your Nebula X1 Pro, the bass is powerful and the surround sound is immersive; but once you connect a PS5, Blu-ray player, or computer, the sound becomes flat and thin, as if only two speakers are working, and even your expensive subwoofer seems to have stopped functioning?

Don't worry, this is most likely not a device malfunction, but rather that you haven't selected the correct Audio Output Format. Today we'll discuss the underlying principles and how to solve this issue.

1. Core Knowledge: LPCM vs Bitstream

1.1 LPCM (Linear Pulse Code Modulation)

What is it: An uncompressed raw audio format.
Characteristics: High fidelity, but massive data volume.
Current Status: Due to the MTK chipset limitations, the HDMI interface on the Nebula X1 Pro can only process 2 channels (stereo) when receiving LPCM input. This results in the loss of bass and surround information, naturally leading to a lack of atmospheric sound.

1.2 Bitstream / Dolby Digital - "Vacuum-Sealed Package"

What is it: Encoded and compressed audio format (such as Dolby Digital, Dolby Atmos).
Characteristics: Data is packaged and compressed with a small file size.
Current Status: The Nebula X1 Pro excels at processing this compressed data. As long as it receives this compressed format, the internal decoder will decompress it and restore the powerful multi-channel surround sound.

2. Why Does "Poor Audio Quality" Occur?

Root Cause:

Many external devices (such as PS5, Sony Blu-ray players) have LPCM (Auto/Uncompressed) as their default audio output setting.

When you connect to the X1 Pro, the device sends unpacked multi-channel LPCM signals, but due to the HDMI interface limitations of the X1 Pro, it can only receive the left and right channels. This results in thin sound without bass (because the bass signal in other LPCM channels is discarded).

Why are built-in apps fine?

Because apps running inside the X1 Pro (such as Netflix, YouTube) process audio directly within the system without going through the HDMI interface "bottleneck," they can perfectly output 5.1/7.1 channels.

3. Solution: Modify Audio Settings on External Devices

Switch from LPCM to Bitstream (Dolby/DTS).

3.1 For PlayStation 5 (PS5) Users

PS5 tends to output LPCM by default. Please manually change it:

Path: Settings -> Sound -> Audio Output
Action: Scroll to the bottom and find "Audio Format Priority"
Selection: Choose only Dolby or DTS, never select Linear PCM
Result: After modification, you will immediately hear the subwoofer kick in and surround sound return

3.2 For Sony/Other Brand 4K Blu-ray Players

Path: Settings -> Audio Settings -> Digital Audio Output
Action: Set the output mode to Bitstream
Note: Ensure the Dolby Digital option is enabled, and do not enable the "Downmix" function

3.3 For Fire TV / Apple TV / Chromecast

Most streaming sticks are usually set to "Auto" and can typically recognize correctly. If you encounter stereo-only sound:

Enter audio settings and manually change the audio format from "Auto/LPCM" to Dolby Digital Plus or Dolby Digital

4. Special Case: Nintendo Switch

Nintendo Switch requires special explanation:

Current Status: Due to Switch's special hardware design, it only supports LPCM format for 5.1 surround sound output and does not support Dolby packaged output
Result: Since the X1 Pro's HDMI interface cannot receive multi-channel LPCM, Switch can currently only achieve 2.0 stereo when connected to this device
This is a hardware-level compatibility limitation, and there is currently no simple software setting to bypass it. We recommend Switch users connect external speakers directly to the Switch or accept the current stereo output