If you are using the Yamaha speakers with the Tyros or Genos models then you are totally castrating the sound of the keyboards, (The recommended speakers are abysmal) which is why most dealers just give them away with the keyboards just to get shot of them. (The sound bar on the Korg PA series also sucks)
If you want to get the best out of the keyboards, get some studio monitors within your price range and you will be blown away by how much better the keyboards sound. (Don’t worry about a sub in a domestic environment as even the cheap studio monitors go deeper than the Yamaha sub)

Bill