Suggestions on a sub (possibly second hand) for my SA30

Hi I recently bought a SA30 and now thinking of connecting a Subwoofer to it. Spent all money on the new amp…so thinking a secondhand sub. I have a pair B&W 604 S3 as my mains. My room is not huge. If I purchase a well looked after sub any suggestions on specs that you may suggest or brands/models) which work well with SA30 or may complement the speakers I have…music in the main comes from turntable my Rega P3 or from streaming from the SA30. I do have my TV connected via the eARC HDMI connection. Appreciate any suggestions around the subs ie. both around what to buy and also optimum setup…e.g. should I use of DIRAC etc or do manually? Many thanks in advance Cheers Peter

my bad. using the denafrips this way will require an external streamer. not what you want. sorry I can’t help.