Sound Quality & Palette Customizing

[Lightcatcher]

First of all: Thanks for this awesome piece of software! I'm using GB,GBC,GBA emulators since 2009 (VBA, VBA Smooth & VBA-M) and just discovered mGBA yesterday. Today I gave it a shot and now I'm really amazed. In less than 2 hours of testing mGBA became my favourite. Impressive!
VBA don't have filters, VBA Smooth is buggy with some games (freeze when using dungeon map in Zelda OoA/OoS e.g.) and always shows a black bar at the bottom edge. VBA-M feels laggy against VBA and VBASmooth.
But mGBA doesn't show any of these problems. It even works with games that crashes with VBA-M! And the visual quality (after some filter adjusting) is the best I've ever seen in GBA emulators. So... thanks! 

There are just 2 issues for me. But I'm sure this is the right place to clear them.

1) Most important: Sound Quality
In comparison with the VBA emulators mGBA sounds worse. Especially with GB and GBC games. The sound is slighty distorted (good to hear with deeper tones) and just misses the clarity I have with the VBA's. And is it normal that "SDL" is the only option for "Audio driver"? Is there any workaround to get a better audio quality?
I'm using an external usb sound card (FiiO E10K Olympus 2).

2) Palette Customizing
The option to change the colors of the background and the sprites was my favourite feature of the VBA's. In mGBA I just found the option to save palettes from games but not to change them. Am I blind or is this a feature that doesn't exist at the moment? If not: Is this on your agenda? Pleeeeeaaaase! 

Thanks a lot!
Greetings from Germany

Lighti

[endrift]

1) GB/GBC audio is still...not so great. It's odd though, since VBA's audio always sounded murky to me due to the low pass filter it applies.

2) This feature doesn't exist yet. It's planned, but I haven't gotten to it.

[Lightcatcher]

Thanks for your fast reply! 

Good to hear that you're aware of these issues (and are working on it?).