This is all fine but you are still limited with Bluetooth which is why no one really makes large Bluetooth systems but simple portable devices. As stated before bandwidth with Bluetooth is limited in he first place so you will not get the sound you would over a wireless 5ghz signal and there is still the range of Bluetooth which is very limited. Although it has improved in distance it is still not ideal. If I am going to want to run a larger system, I would definitely want the quality and Bluetooth will not give you that. Stick with either hardwiring your speakers with a docking station or jack or go wireless. If you are going for portability and small footprint and just want to listen to music without true fidelity but just have music then Bluetooth is the answer. Example of the lack of bandwidth would be shown in the transfer of a photo from one device to another: it takes a little time to transfer that picture than it would over Wi-Fi. Also most Bluetooth devices can be purchased from very cheap to somewhat expensive. Even with the expensive versions you will not get the immersive sound you would over Wi-Fi. As said before as well Bluetooth is a somewhat secure connection and thus less interference in the connection while playing music. If you just want more speakers to play then there are Bluetooth series speakers out there that connect to each other via a wired connection. I use these and create a pyramid of sound as I like to call it. Like I said don't expect much but its plenty for just working around the house or just relaxing. Also the output connection on the back of some Bluetooth speakers can be used to hook to a amped subwoofer if you really want the lows. Again not an Ideal setup if you want fidelity but it works just fine for basic needs. If you're an audiophile well you wouldn't be using Bluetooth anyway. So basically your options are software running mono even when it says stereo over Bluetooth or a speakers that allow hardwiring to another speaker via a jack or for those really good tunes Wi-Fi or a true hardwire system. Research and you will find many choices, as far as OSX goes, its a great operating system but not a real good choice if your just wanting to run multiple speakers, unless of course you want to buy an overpriced computer system just to run Bluetooth speakers. Apple is awesome when it comes to video and audio abilities but not the solution for someone just wanting to extend more than one Bluetooth device. Neither is buying a windows computer if you are just running off of your phone.
There is a lot of technology out there, read up on it and find a solution that best works for you