There's a kind of rumour that sound systems in BsAs are not that good. Does this suggest that sound systems elsewhere, in London, say, are far superior? Because I don't think they are necessarily.
Many of the halls that are home to milongas in BsAs are home to nothing else: they have milongas night after night, with different Djs and organisers, so it's likely that the systems have evolved to give the best possible sound. Sadly, this is never the case in London, where organisers can face the trouble of setting up speakers and amplifiers, and removing them at the end of the evening. The set-up might be adequate or not, even if the equipment is excellent.
Salon Canning is an interesting example of a hall which functions as both a milonga and, because it is so extensive, as a place where people sit and chat. There's never room on the dance floor for everyone who is there: you dance in shifts, so to speak. The square dance floor is at the centre of a massive square room, and the speakers are on a rig over the floor itself, so the music is angled down onto the floor from all four sides. This works well: the dancers have sufficient volume of music, while people sitting around the sides of the floor aren't so deafened that they have to shout at each other. Moreover, the system delivers excellent bass, so the dancers get a strong rhythm. It may be that the equipment in Canning isn't the best, but it's certainly well organised. The upper register of music is much the same pitch as conversation, and if people can't hear themselves talk because of the high notes, they simply shout louder. As people drink their voices get louder anyway, but this may be less of a problem at Canning, where you might have to wait half the evening for the waiter to deliver your drink!
Some smaller halls in London have built-in speakers which aren't necessarily focused on the dance floor, but so long as the bass is strong and clear the volume doesn't need to be high, and a strong bass conflicts less with conversation. It tends to be larger venues that are more difficult to organise for good sound.