The sound on these units is one of their biggest let-downs unfortunately. The standard equaliser is configured to be quite biased toward higher frequencies, which goes hand in hand with most of Chinese pop music I guess
Anyway, if you installed Malaysk's ROM, then you probably have root, so in that case I recommend using Viper 4 Android software sound processor (
https://play.google.com/store/apps/details?id=com.vipercn.viper4android_v2_fx&hl=en_GB). This app comes with a sound driver that, once installed, will allow you to tune the sound EQ settings for much more low and mid-range sound and this will apply to any app within the Android OS, not just PowerAmp. This will not apply to the FM Radio though, as the sound from the radio hardware module is sent directly to the hardware amplifier, bypassing the Android OS and the Viper app completely. The Radio app is like a remote for the module, which is controlled via the MCU firmware/hardware outside of the OS.
The other reason for low bass with these units is the fact that the signal sent to the rear amp that drives the sub and rear speakers seems to be lower than stock Audi/Bose (this is the case for all after-market systems), which requires you to fade to the back a little more in order to drive the sub a little harder. This is the biggest reason why you don't seem to hear much bass.
A better way of resolving all of these problems is to use a standalone sound processor unit (DSP). The good DSPs can take the normal speaker output from the head unit (high-level output), de-equalise it, apply your pre-set EQ settings to that and output a clean signal as Hi-level signal (directly to speaker) or adjustable low-level signal (to the amp). This option is the most expensive one, with prices for DSPs ranging from about £100 (miniDSP MDSP-24) to a few of hundred (Audison bit ten D being the best one to go for, but requires professional configuration)
My current setup is using the Viper 4 Android app and seeing as I never listen to radio, it works fine for my needs. My long-term objective is to have this combination:
Herts HSK 165 for front speakers
10" Sub in the boot
Audison bit ten D DSP
Hertz HCP4 Amp to drive the speakers and sub