How To Video by @ISF
So, Samsung Galaxy S9 was launched, with an AKG tuned Stereo Speaker. A definitive upgrade from a single bottom firing Speaker on S8 & S8+
but, luckily for us, S8 & S8+ (Exynos Variant) user, there's a way to at least get a similar audio experience on our phone.
This is achieved by enabling our "earpiece speaker" as a secondary output. Creating a pseudo-stereo experience. Sure its nothing when compared to real stereo on S9, but hey, at least we got something right ?
So, how do we get that ? It's simple. We need to modify some lines on mixer_paths.xml file located in system/etc/
but lets make that easier, by providing a Magisk Module & TWRP flashable .zip for you to use.
For you Magisk User, simply download the GalaxyS8DualSpeakerMagiskModule from attachment, and flash it through your Magisk Manager.
If you use SuperSU, you can use TWRP zip also from the attachment, and flash it from your recovery.
Both file support latest OREO firmware and Magisk 16. (If you are still on Nougat, download Nougat version from attachment)
Now, to make it even better, you can then install Audio Mod to your S8, like Viper4FX or A.R.I.S.E the effect will applied to both of the speakers.
For Advanced User :
If you need to adjust the gain yourself, find these lines in mixer_gains and adjust the 35 or 40 value to your liking :
<ctl name="HPOUT3L Input 1 Volume" value="35" />
<ctl name="HPOUT3R Input 1 Volume" value="35" />
<ctl name="HPOUT2L Impedance Volume" value="107" />
<ctl name="HPOUT2R Impedance Volume" value="107" />
<ctl name="HPOUT2L Input 1 Volume" value="40" />
<ctl name="HPOUT2R Input 1 Volume" value="40" />
Flashable TWRP & Magisk ZIP by me & @LinkseD.
Thank you @silvercat who brought this info on another device thread, and to @topjohnwu who made the systemless method for this mod possible through his Magisk creation.