I was able to run a room response curve on the recommended setup. My room has no acoustic treatment, so the frequency response is a bit uncontrolled. Nevertheless, the total range was only(?) 23 db. The signal from 40Hz to close to 2kHz is in a 15db band, but then it flattens out at a lower level (about 7db) but only a 6db band to about 15kHz, kind of like a shelf.
Off the top of my head it looks like I can lower the gain in the ULS-15s a few db but there is a peak at 200Hz I have to figure out how to control. Cross-over is at 80Hz so this is probably some room reflection coming from the HB-1s. However, it is sharp enough I may be able to ignore it.