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^This, or get an Airport Express. You might find the Bluetooth receiver a bit cheaper though.
 
I had exactly the same issue as you, but with the Bose companion 3 speakers.

Originally I bought a Bluetooth box which I just pluged in via aux to connect to my MacBook Pro. Really easy set up, but as soon as I started playing any music, the quality was just really disappointing. I'm no music expert, but even I could tell the difference compared to having a wired connection.

I returned it straight away and purchased an AirPort Express purely for its airplay features. It's awesome! I've had it over a year now and it still amazes me how well it works and how great the quality it.

Definitely worth it in my experience.
 
I have Bose companion 5 as well and I would like to know if someone who has successfully connect thru airport express. Bose companion 5 can only input by USB and from what I read airport express doesn't recognize it thru usb
 
I have Bose companion 5 as well and I would like to know if someone who has successfully connect thru airport express. Bose companion 5 can only input by USB and from what I read airport express doesn't recognize it thru usb

USB won't work. But doesn't the Companion 5 have an auxiliary input in the control pod?
 
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