Drop in audio quality after screen display change
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GL 350 Bluetec 2015
Drop in audio quality after screen display change
Hi!
I've a 2015 GL 350. It's got premium B&O sound - very clear sound and good bass.
I had an aftermarket screen installed yesterday that has in built Android Auto and Apple Car play. I use Spotify lossless quality and have a keen ear for good sound. After the install I noticed that the sound seems amped up and though it still sounds good, there is a significant drop in quality. Notes are more shrill and bass is more boomy. Not enjoying turning up the volume. I've tried all settings but there is a considerable drop in quality post install.
I spoke with the tech who said that the screen/module is just the display and the audio is still through the original car Bluetooth (MB Bluetooth) so there's no way an aftermarket Android auto/car play screen unit will impact audio output.
I can swear that the sound quality has dropped a lot. Any thoughts?
I've a 2015 GL 350. It's got premium B&O sound - very clear sound and good bass.
I had an aftermarket screen installed yesterday that has in built Android Auto and Apple Car play. I use Spotify lossless quality and have a keen ear for good sound. After the install I noticed that the sound seems amped up and though it still sounds good, there is a significant drop in quality. Notes are more shrill and bass is more boomy. Not enjoying turning up the volume. I've tried all settings but there is a considerable drop in quality post install.
I spoke with the tech who said that the screen/module is just the display and the audio is still through the original car Bluetooth (MB Bluetooth) so there's no way an aftermarket Android auto/car play screen unit will impact audio output.
I can swear that the sound quality has dropped a lot. Any thoughts?
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From: USA - Minnesota
2014 GL350
Assuming that your phone is wirelessly connected to the Android Auto/CarPlay screen, that connection is via a private wifi network after an initial bluetooth handshake.
Thus, your new screen is now responsible for whatever processing (or lack thereof) that occurs between receiving the audio stream from the phone and sending it back out via Bluetooth to the car. Also note that Bluetooth audio codecs are “lossy” (at least on 2015 vintage cars) so you’ll NEVER get lossless quality if there is Bluetooth in your audio chain. In addition, all these myriad aftermarket AA/CarPlay units are designed to be cheap and the target demographic is not audiophiles.
As a result of all of the above, there are multiple steps in the audio chain where undesired changes to audio quality can occur. I’m gonna suspect that *IF* you were using the car’s original Bluetooth previously with Spotify from your phone that your phone was doing a better job of compression for Bluetooth or sending a higher-quality, but still lossy, stream. Or perhaps both.
(FWIW, I have a aftermarket CarPlay unit in my 2014 GL that retains the OEM screen and uses the car’s wired AUX port instead of Bluetooth so there is more than one way to skin the cat. And the AUX port is not perfect, either.)
Last edited by cadetdrivr; Oct 24, 2025 at 09:58 AM.
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GL 350 Bluetec 2015
Yup.
Assuming that your phone is wirelessly connected to the Android Auto/CarPlay screen, that connection is via a private wifi network after an initial bluetooth handshake.
Thus, your new screen is now responsible for whatever processing (or lack thereof) that occurs between receiving the audio stream from the phone and sending it back out via Bluetooth to the car. Also note that Bluetooth audio codecs are “lossy” (at least on 2015 vintage cars) so you’ll NEVER get lossless quality if there is Bluetooth in your audio chain. In addition, all these myriad aftermarket AA/CarPlay units are designed to be cheap and the target demographic is not audiophiles.
As a result of all of the above, there are multiple steps in the audio chain where undesired changes to audio quality can occur. I’m gonna suspect that *IF* you were using the car’s original Bluetooth previously with Spotify from your phone that your phone was doing a better job of compression for Bluetooth or sending a higher-quality, but still lossy, stream. Or perhaps both.
(FWIW, I have a aftermarket CarPlay unit in my 2014 GL that retains the OEM screen and uses the car’s wired AUX port instead of Bluetooth so there is more than one way to skin the cat. And the AUX port is not perfect, either.)
Assuming that your phone is wirelessly connected to the Android Auto/CarPlay screen, that connection is via a private wifi network after an initial bluetooth handshake.
Thus, your new screen is now responsible for whatever processing (or lack thereof) that occurs between receiving the audio stream from the phone and sending it back out via Bluetooth to the car. Also note that Bluetooth audio codecs are “lossy” (at least on 2015 vintage cars) so you’ll NEVER get lossless quality if there is Bluetooth in your audio chain. In addition, all these myriad aftermarket AA/CarPlay units are designed to be cheap and the target demographic is not audiophiles.
As a result of all of the above, there are multiple steps in the audio chain where undesired changes to audio quality can occur. I’m gonna suspect that *IF* you were using the car’s original Bluetooth previously with Spotify from your phone that your phone was doing a better job of compression for Bluetooth or sending a higher-quality, but still lossy, stream. Or perhaps both.
(FWIW, I have a aftermarket CarPlay unit in my 2014 GL that retains the OEM screen and uses the car’s wired AUX port instead of Bluetooth so there is more than one way to skin the cat. And the AUX port is not perfect, either.)
Thank you very much for your reply. Very helpful indeed. Even if I use Android Auto with a wired connection, the audio is still not good. Previously I had a module for Android Auto using the original display screen and the audio was much better.
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From: USA - Minnesota
2014 GL350
I’m gonna suspect that your previous box was using the AUX port or was simply doing a better job of internal processing and compression. And even the AUX port is not a perfect solution, either, since it’s an analog input so the audio experiences a digital-to-analog conversion in the box followed by an analog-to-digital in the car.
I’d look in the settings menu on the new screen (both Android Auto and the hardware device) to see if there are any selections for different audio processing options or bluetooth specs, but I’d be pleasantly surprised if there were any.
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GL 350 Bluetec 2015
Thanks again for your valuable suggestions. No settings of those sort available unfortunately. I am now more aware as a result of your feedback and will discuss this further with the tech. I plan to give back the screen and has have an Android Auto box installed with the original screen. Will ask them to check out the Aux port vs Bluetooth suggestion
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From: USA - Minnesota
2014 GL350
But yes, if using the MB AUX input from an analog source (audio jack on phone, for example) I can see where this suggestion would have merit.
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MBWorld Fanatic!
Joined: Jan 2014
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From: USA - Minnesota
2014 GL350
Thanks again for your valuable suggestions. No settings of those sort available unfortunately. I am now more aware as a result of your feedback and will discuss this further with the tech. I plan to give back the screen and has have an Android Auto box installed with the original screen. Will ask them to check out the Aux port vs Bluetooth suggestion
For the GL, I purchased a and and was pleasantly surprised that the included wire harness plugged directly into the unit and the back of the Comand unit. No splicing required and AUX was hard wired in the harness. This was a couple years ago and there’s now LOTS of aftermarket CarPlay units out there. This was in 2021 so I don’t know what’s the “best” product out there now or if RoadTop has made any changes to their product.
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GL 350 Bluetec 2015
The tech refuses to believe that the aftermarket screen can impact sound and shared the following from ChatGPT:
Excellent clarification — and that actually makes a big difference. If you are still using the exact same Mercedes OEM Bluetooth module (the one integrated into the original COMAND or factory head unit) — meaning your new Linux screen is not handling the Bluetooth audio itself, but rather the OEM system is still pairing with your phone and streaming audio through the factory B&O amp — then: 👉 No, your sound quality should not change at all. Here’s why: 🎯 1. The audio chain is unchanged If your phone → OEM Bluetooth → OEM B&O amp → speakersremains exactly the same, the entire digital and analog path that defines your sound quality is identical to before. The new Linux screen, in that case, is only acting as a visual interface — it’s not touching or processing the audio signal. 🧩 2. The OEM Bluetooth module handles everything That module determines: • The codec (likely SBC or AAC) • The bit rate • The DSP routing into your B&O amplifier Since you haven’t swapped or bypassed it, your audio fidelity, tonal balance, and dynamics remain the same as before.
Excellent clarification — and that actually makes a big difference. If you are still using the exact same Mercedes OEM Bluetooth module (the one integrated into the original COMAND or factory head unit) — meaning your new Linux screen is not handling the Bluetooth audio itself, but rather the OEM system is still pairing with your phone and streaming audio through the factory B&O amp — then: 👉 No, your sound quality should not change at all. Here’s why: 🎯 1. The audio chain is unchanged If your phone → OEM Bluetooth → OEM B&O amp → speakersremains exactly the same, the entire digital and analog path that defines your sound quality is identical to before. The new Linux screen, in that case, is only acting as a visual interface — it’s not touching or processing the audio signal. 🧩 2. The OEM Bluetooth module handles everything That module determines: • The codec (likely SBC or AAC) • The bit rate • The DSP routing into your B&O amplifier Since you haven’t swapped or bypassed it, your audio fidelity, tonal balance, and dynamics remain the same as before.
