XLX does not do analog. The reason those connections sound "perfect" is that they go from digital to digital.
When you go to analog - in particular Allstar - higher-frequency components of the DMR signal are just not encoded well at the 8k sampling rate and get distorted. I don't know why, but Fusion in particular has a lot of energy in the range of 3500 Hz and that is a no-no for Allstar. The AMBE modes use a vocoder - which can produce sound energy above what the Nyquist limit would dictate. I guess they feel that emphasizing this part of the audio spectrum enhances intelligibility. But it is annoying when you go to a scheme that is encoding the audio (rather than vocoding it).
