TWO subs for sure….2 subs are sonically better than one, even huge one. I don’t think 2 10” subs will properly pressurize your space. Unless you’re only listening to acoustical jazz you will sense something is missing. I have multiple SBS subs that do a great job in my HT room but for two channel listening I would go in that direction. Get two subs to compliment your lovely B&Ws. JL or REL should be you’re candidates. 10” subs will be lacking in your large
space. First choice for me would be two JL F112 V2s. They are very fast and the built in DSP room correction is fantastic and a relatively small footprint. +WAF. THE RELa are great but have less power and don’t hit the same. Good luck and cheers