I built a full marty sub box a few years ago and ran it with an iNuke amp and used the DSP to set a HPF and it sounded great. Now I have replaced that sub with a pair of vented end tables and I am giving the old full marty box to my brother and he is going to put a single Dayton Classic 15" in it and use an old plate amp off of another sub he is currently using. The issue is that he does not have a HPF anywhere to protect the sub from self-destructing around the 14hz range. He is putting this together on the cheap and does not want to buy a Mini DSP, but I don't know the chances of him actually blowing the sub. I don't know how many movies or songs actually have bass this low. Do you think he would be safe without a HPF, or is it absolutely necessary? Thanks.