My B&W 800 series speakers belong to those brands often associated with listening fatigue. There is no denying that, indeed, B&Ws, in general, have an open character and can sound very bright.... the diamond tweeter is merciless. But the truth is that listening pleasure vs. listening fatigue depends on some factors:
1) A synergistic combination with amplification or not.
2) The character, luminous or amber, of the source.
3) Appropriate passive treatment (carpets, curtains, furniture, etc., etc.) in the listening room or not.
4) Your personal taste.
Naturally in some cases the software can be more open, and a balanced set-up should highlight this, but in any case it should never make you perceive listening fatigue. If this were the case, we would need to understand where to intervene to eliminate the problem.
My 2 cents.
Pietro