When I bought my first set of bookshelf speakers, the modest Edifier R1700BTs, I specifically sought out a pair that could be easily linked with a subwoofer. The speakers have a built-in subwoofer output and a digital-signal processor that routes frequencies under 140Hz to a connected sub. I eventually added the Edifier T5 subwoofer to the R1700BTs, which significantly improved low-end performance. That sub stayed with me as I built a new Dolby Atmos home theater system — until I realized it was doing more harm than good.