High-Pass Output
A high-pass output sends the main speakers or their amplifier a signal with low frequencies attenuated by a filter.
On a subwoofer, this can form part of bass management: the subwoofer handles the lower band while the filtered output feeds the main-speaker path. It is different from an unfiltered pass-through.
High-Pass Output — Subwoofer
High-pass filtering can reduce the bass demand placed on the main speakers. The output may be at line level for an amplifier or active speakers, or at speaker level where the design supports it. Its crossover frequency and slope determine how progressively low frequencies are reduced.
Compare the actual filtering, signal level and adjustment options with the rest of the system. An RCA or XLR output labelled link, thru or line out is not necessarily filtered. The subwoofer's own low-pass control does not by itself confirm a high-pass output, and matching the two paths still requires appropriate level and phase alignment.