These guys at Max Tech always do a great job at comparing speakers. Skip to 5:48 to hear the sound comparison. To summarize, the 11 Pro Max has greater frequency range which makes the XS Max sound flat. But the volume wasn’t too different to my ears.
I noticed a difference.. only played 39 seconds of Andersen .Paak, and I hear more separation between the instruments and more clarity... will perform a more involved session with some hi res tracks later.