Equalizer Alternatives for Huawei Devices

For Huawei devices there are two alternatives to configure equalizer settings:

Huawei's original Histen sound technology (for the latest devices such as Mate 10 and Honor 9)
Android's standard equalizer API (for relatively old devices such as Mate 9 and P10)

Huawei's Original Histen Sound Technology

Builtin GUI is avaiable to configure equalizer settings.
https://www.gadget-manual.com/huawei/sound-settings-in-honor-9/

Android's Standard Equalizer API

There is no builtin GUI, but third party apps are available to call the standard API.

API spec:
https://developer.android.com/reference/android/media/audiofx/AudioEffect.html

Sample equalizer app:
http://kevinboone.net/android_simple_eq.html

If Histen Equalizer is Available, Standard Equalizer Does Not Work

Third party equalizer app does not work well on Honor 9, on which device Histen Equalizer is supported. On enabling Bass Boost, low tone emitted from earphones completely disappears. Probably the two equalizer functions conflict with each other.
https://club.hihonor.com/in/honor-9-lite.321/poor-sound-using-external-equaliser-app-in-huawei-9-lite--help--.83911

Even If Histen Equalizer is Unavailable, Standard Equalizer Does Not Work after Updating to Oreo (Why???)

Surprisingly, after updating to Oreo, the same issue happens on Huawei Mate 9, on which device Histen Equalizer is not supported.
https://forum.xda-developers.com/p10-plus/help/equalizer-broken-oreo-update-t3749336

I suspect Histen Equalizer function was merged into the mainline source code of Huawei's Android Oreo (EMUI 8), though this function is disabled on Mate 9.

Any Solution?

Currently there is no solution to the issue on Mate 9 and P10. Once Updating to Oreo on these devices, we can never configure equalizer settings correctly.

I reported the issue to Huawei official support center, but I do not know if the issue will be fixed. I do not reprint the reply from Huawei official support center, because Huawei prohibits presenting communication log between Huawei and customers to public.

(update) At Last the Problem Fixed by Updating to Android Pie!

I confirmed the malfunction of bassboost was fixed on my mate 9 by updating OS to android pie.