While I agree that most speakers are improved by the addition of sub(s), the Ref 1s can go far lower than their specs suggest. Typical in room response (if you have some support from the port reflecting off the back wall) will go to the lower 30s. Not full range, but still pretty deep. They can also play much louder than the LS50s.
Perhaps the best approach is to try them w/o your current sub vs with it and see what you prefer.
They’re really nice speakers. Enjoy!
