A:AnswerThis unit is designed for connecting passive (unpowered) speakers. BUT, the input on your sub MAY be able to accept that. (If the input on your sub is "Speaker" wire inputs.) Any other type of connection, no.
A:Answer"Best?" That's, ahem. . . a loaded question. In most simple terms; ANY self-powered (active) sub can be used. It's just a matter of hookup method. This unit has RCA-type output for the sub. Lookup (google) articles on choosing a subwoofer. Be prepared for numerous and varied opinions, however.
A:AnswerMost TV's have one HDMI input that is and ARC connection, that goes to the same input on the back of the receiver. That runs your TV through the receiver at all times.
A:AnswerHi, geoff! For more information about the manufacturer's warranty, please refer to this link:
https://docs.sony.com/release//Warranty_459910711.pdf
~Ralph