Found one feedback by Kwong at jumpic.com
"HiBy R6 Pro - the same shape, stainless steel casing is more refined, I prefer the 4.4mm port, the sound I feel more smooth, the resolution is better, and the sound field seems to be wider, both It is the improvement of some details and the style remains unchanged. "
"HiBy R6 Pro - the same shape, stainless steel casing is more refined, I prefer the 4.4mm port, the sound I feel more smooth, the resolution is better, and the sound field seems to be wider, both It is the improvement of some details and the style remains unchanged. "