For the Yamaha its 5th Avenue. I just don't know if they are still open.
Re Sonos Beam...I have the Sonos Playbar and while it sounds great, your option in adding a sub is going to be very expensive since the sub that can only work in the Sonos sound bar ecosystem is the Sonos Sub which is $800.00. To tell you honestly that Sonos Sub isnt worth $800.00. With the Yamaha...you can add any sub that you like since it has a sub out RCA. An SVS SB1000 is only $500.00 and it will blow away the Sonos Sub in terms of performance.