There are proponents of each method. High-passing relieves the Ref and it's power amp of having to reproduce lower frequencies, which will improve the midrange sound quality of both. Does that come at a cost? Purists don't like to add any active electronics to the signal chain, especially ones thought to contain sound quality-compromising parts or circuits.
The Marchand passive filters use questionable (to some) techniques to get the job done; their active filters are more highly thought of. If you can find a First Watt B4, it's a great little, modestly-priced ($1500 retail) x/o, featuring all discrete parts: no opamps, no IC's. 1st/2nd/3rd/4th-order high-pass and low-pass filters in 25Hz increments from 25Hz to 3200Hz, and level controls for one of the two filters (for bi-amping with power amps of different input sensitivities).