In ultimate vocal remover GUI, you can easily use an integrated method to separate different audio tracks (using a combination of different models in parallel to process the input audio, and then selecting different integrated algorithms to get the final output audio); I found that there are musical instrument sounds (like dongxiao and erxian, etc.) in the vocals separated by a single model. This may be because their frequency spectrum partially overlaps with the vocals, resulting in the separated vocals being unclean.