I am using 4 ULS15s in my HT and the output and LFE extension are outstanding! I have measured rising response (with REW and a calibrated mic) below 20Hz to at least 10Hz due to room gain. Those are in walnut, sadly no longer offered, but I have one in "basic" black in another room. Nothing "basic" about that finish - not piano black but certainly not truck bed liner either. Very attractive.I love my ULS15. Of course, I keep reading about the benefits of two subs, but haven't broken the news to the wife yet - on that subject, should they be the same model, or should the second be 'tailored' to a particular 'need' in the room? i.e. a smaller 8" in combination with the 15"?