After trying out a lot of different sound mods and apps and patches I always came back to Viper4Android. Simple to use, great sound quality and a lot of customization. Steps:
Flash the attached Magisk module (v4afx_v1.7.3.zip) through Magisk Manager and press volume up button twice.
After that reboot your device and enter the Viper4Android app.
Next, you need to set up the sound mod.
*I only use Viper4Android for my headphones so I will cover only that part but you could test out different settings for other audio outputs*
In the Viper4Android's menu go to UI setting and set it to expert.
Go to Headset and click Enable, I suggest you put on your headphones now so you can hear the changes in the sounds yourself and tweak them to your liking.
My settings on Redmi Note 5 Pro are: Spectrum Extension (enabled): Strength: 0,5 FIREqualizer (enabled): Preset: Acoustic Convolver (enabled); Impulse Response: BBE2.irs (extract the attached BBE 2.zip into Viper4Android/Kernel); Cross Channel: 30% Dynamic System (enabled); Listening Device: High-end headphone v2; Dynamic Bass:5% Viper Bass (enabled); Bass mode: Natural bass; Bass Frequency: 100 Hz; Bass Boost: 3,5 dB Viper Clarity (enabled); Clarity mode:Natural; Clarity:6 dB