I have a modest sized room (4m by 4m) with 4 seats, TV, 10 yr old Yamaha av amp and 5x Bose acoustimass (twin cube) speakers that are also about 10yrs old.

The acoustimass system has a separate bass speaker unit that assists all 5 of the little speakers. It is not really a sub, but it provides mid range for the little twin cube speakers. As it is in a small room it has enough grunt to produce a bit of a rumble and I have used it this way for years.
My amp has 2x sub outputs, neither of which are being used at the moment

This is obviously a long way from an audiophile system. My ears aren't the best anyway. Little speakers work fine in this room
Looking for a sensible, genuine subwoofer to turn this 5 channel system into a 5.1
Happy to buy new or second hand
Don't want to break the bank. Few hundred quid maybe
Any suggestions pls ?
Thank you

The acoustimass system has a separate bass speaker unit that assists all 5 of the little speakers. It is not really a sub, but it provides mid range for the little twin cube speakers. As it is in a small room it has enough grunt to produce a bit of a rumble and I have used it this way for years.
My amp has 2x sub outputs, neither of which are being used at the moment

This is obviously a long way from an audiophile system. My ears aren't the best anyway. Little speakers work fine in this room
Looking for a sensible, genuine subwoofer to turn this 5 channel system into a 5.1
Happy to buy new or second hand
Don't want to break the bank. Few hundred quid maybe
Any suggestions pls ?
Thank you