I have a somewhat SPC related question but it's more concerning BRR samples.
I started ripping WAV samples from PSX and DS RPGs and I would like to know the best sampling rate by taking in account the size vs quality factor. I changed some FFIV DS samples to 16 bit at 16000Hz. I haven't really noticed too much change in the quality but when I dropped to 8000Hz there was a significant drop of volume and quality. So what would be the best sampling rate for my WAV samples that will be converted into BRR samples after? What is the ideal sampling rate for the SPC-700?
Also, as for GBA sample is the audio quality of the GBA is that bad that it I shouldn't spend my time on those?

I read somewhere that the quality of the GBA sound is 8 bit at a average sampling rate of 8000Hz...
Thanks