How to enable aptX on Xiaomi Mi 9T: unlock Hi-Res Audio

Why AptX is Important for Xiaomi Mi 9T and How to Activate It

Xiaomi Mi 9T (also known as Redmi K20 in some regions) is equipped with a Qualcomm Snapdragon 730 processor, which supports advanced audio codecs at the hardware level, including aptX and aptX HD. However, by default, the manufacturer disables these functions in the MIUI firmware - ostensibly for "stability", as a result, users are deprived of the ability to transmit high-resolution Bluetooth audio, which is especially critical for music lovers and owners of premium wireless headphones.

In this article, we will discuss three officially confirmed ways to activate aptX on Mi. 9T, including methods through the engineering menu, ADB-Important: the procedure requires care, because the wrong actions can cause malfunctions in the Bluetooth module. MIUI 14 and Android 12, but are also suitable for newer versions (taking into account the features of the new version).

Before you start, check if your headphones support aptX.The list of compatible models includes:

• 🎧 Sony WH-1000XM3/XM4/XM5 (aptX + aptX HD)
• 🎧 Sennheiser Momentum 3 (aptX Adaptive)
• 🎧 Bose QuietComfort 45 (aptX Low Latency)
• 🎧 Audio-Technica ATH-M50xBT (aptX)

If your model is on the list, you can start setting up.

Method 1: Enabling aptX through the engineering menu (without root)

The safest method is to activate codecs via the hidden engineering menu ##36446337# (or ##ENG##) which does not require superuser rights and works on most MIUI firmware, but can reset after a system update.

Step-by-step:

1. Open the Phone app and enter the combination ##36446337##.
2. In the engineering menu, go to Hardware Testing → Audio → Bluetooth Audio.
3. Find the Bluetooth Codec and Bluetooth Sample Rate options.
4. Install Codec: aptX (or aptX HD if supported) and Sample Rate: 48000 Hz.
5. Save the settings and restart the smartphone.

After the reboot, check the active codec in the Bluetooth settings:

1. Put the headphones on the phone.
2. Open Settings → Bluetooth.
3. Click on the gear icon next to the connected device.
4. The audio quality section should display aptX (or aptX HD).

⚠️ Note: On some versions MIUI The Bluetooth Audio section may not be on the engineering menu, in which case try the alternative code ##2846579# (Project Menu) → Background Settings → BT Settings.

Method 2: Activate aptX through ADB-Teams (for experienced users)

If the engineering menu does not give access to the settings of the codecs, you can use Android Debug Bridge (ADB), this method requires connecting the smartphone to the PC and basic knowledge of working with the command line.

What you need:

• 🖥️ A computer with installed Xiaomi drivers and ADB Tools.
• 📱 Included debugging by USB on a smartphone (Settings) → The phone. → Version. MIUI → 7 times press to unlock the developer mode, then Settings → Additionally. → For developers → Debugging by USB).
• 🔌 USB-cable (preferably original).

Instructions for activation:

1. Connect your smartphone to your PC and confirm the debugging permission.
2. Open the command prompt (Windows) or terminal (macOS/Linux) in the folder with ADB.
3. Enter the command to check the connection: adb devices must display the serial number of the device.
4. Execute the command to enable aptX: adb shell settings put global bluetooth_a2dp_hw_offload_cap 255 This command unlocks all supported codecs, including aptX and LDAC.
5. Reboot your smartphone: adb reboot

After the reboot, check the list of available codecs in the Bluetooth settings. If aptX does not appear, try the additional command:

adb shell settings put global bluetooth_a2dp_hw_offload_disabled 0

Method 3: Install custom firmware with support for aptX

If standard methods don't work, you'll find a custom firmware option, like LineageOS or Pixel Experience, which often includes support for all the default hardware codecs, but the process requires unlocking the bootloader and can be insecure.

Advantages of custom firmware for audiophiles:

• 🎛️ Full support for aptX HD, LDAC and AAC limitlessly.
• 🔊 Possibility of fine tuning of the equalizer at the system level.
• 🚀 No background restrictions MIUI Bluetooth bitrate.

Step-by-step process:

1. Unlock the bootloader through Mi Unlock Tool (requires a Xiaomi account binding).
2. Install custom TWRP recaps for your model (see instructions on XDA Developers).
3. Download the firmware (for example, LineageOS 20 for davinci is the code name Mi 9T).
4. Flush the firmware through TWRP, having previously made a backup of the current system.

⚠️ Attention: Unlocking the bootloader resets all data on the device! Also note that some custom firmware may have bugs with work NFC Check user reviews on thematic forums before installing.

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Before you run your firmware, save your device's IMEI (you can use the ##4636### → Phone Information) to help restore the network if something goes wrong.

Checking the work of aptX and fixing problems

After activating aptX, you need to make sure that the codec is actually being used.

1. Connect the headphones to your smartphone.
2. Open a music playback app (like Poweramp or USB Audio Player PRO).
3. Run the track playback with a high bit rate (24-bit/48kHz or higher).
4. In Bluetooth headphone settings, check the current codec (should be displayed aptX or aptX HD).

If the codec is not activated, possible causes and solutions:

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If after all the manipulations, the aptX did not work, the problem may be in the hardware incompatibility of your Mi model. 9T With a specific revision of the Snapdragon 730 chipset, you can only wait for Xiaomi to update or consider alternative codecs (LDAC, AAC).

Codec comparison: aptX vs LDAC vs AAC for Xiaomi Mi 9T

Not all users understand why aptX is needed if the default smartphone is using AAC or SBC.

• 🔹 aptX: low latency (ideal for video), bitrate up to 352 kbps, supported by most premium headphones.
• 🔹 aptX HD: bitrate 576 qbps, support 24-bit/48kHz, best quality music.
• 🔹 LDAC: Bitrate up to 990 kbps, but high latency and unstable operation on weak devices.
• 🔹 AAC: balanced codec (bitrate up to 250 kbit / s), but depends on the manufacturer's implementation.
• 🔹 SBC: Basic codec, low quality, but maximum compatibility.

For Xiaomi Mi 9T, the best choice is:

• 🎮 For games and videos: aptX Low Latency (minimum latency).
• 🎵 For music: aptX HD or LDAC (if the headphones support).
• 📞 For calls: AAC (Best compatibility with voice codecs).

Important: LDAC can cause interference with a weak Bluetooth signal. If you notice a crack or breaks in sound, switch to aptX or lower the bitrate of LDAC in the settings (if this option is available).

Frequent Mistakes and How to Avoid Them

When trying to turn on aptX, users often encounter common errors, and here are the most common ones and how to solve them:

1. Error: the engineering menu does not open. Reason: Xiaomi blocks access to the engineering menu on some regional firmware (for example, for Russia or the EU). Solution: Install global or European firmware through the Mi Flash Tool (without data loss if you choose the option "Save user data").
2. Mistake: After ADB-There are no aptX commands. Reason: Some versions MIUI An additional command is required to reset the Bluetooth cache.Solution: Perform: adb shell pm clear com.android.bluetooth Then restart the device.
3. Error: The sound got worse after aptX activation. Cause: Not all headphones work correctly with aptX on the Snapdragon 730 because of the drivers. Solution: Go back to AAC or try calibrating the sound through Equalizer APK (like Wavelet).

⚠️ Attention: On firmware MIUI 13 and newer Xiaomi added protection against changing audio settings through ADB. If the teams don’t work, try to temporarily roll back on the MIUI 12.5 (for example, through Xiaomi Firmware Updater).

FAQ: Answers to popular questions