The majority of the subs I have owned aren’t THX rated: PB-1000, SB-2000 Pro, PB-2000 Pro, SB-3000, PB-3000, PB-4000, SB16, RS13, FV18 and FV15HP but are all good or excel. I follow the Audioholics spreadsheet or older data-bass.com spreadsheet‘s output for comparison.