YES, they 'must' be connected to each other - with the provided speaker cable. These are "active" speakers, with the built-in amp (rated 20 Watts RMS/Channel) for both L and R channels located in the "Left" speaker. As the left speaker only has LINE LEVEL (RCA, 3.5 mm) inputs it should not be driven with a speaker-level signal from your receiver. If you are going to 'drive' your remote speaker set-up with your receiver, you should shop for 'passive' speakers (not self-powered, like these Model: NS-HBTSS116's) For the same $ballpark ($150~$200) I would recommend bookshelf speakers from Pioneer's Andrew Jones speakers Pioneer SP-BS22 (~$129/pair), Wharfedale - Diamond 10.1 (Black) (~$249/pair), or say Andrew Jones ELAC B6 (~$279/pair).