first, bluetooth range is limited to 35ft (10 meters). bluetooth signals are 1Mhz wide, so there's not a huge problem with them sharing spectrum space, but if there are wifi devices present , or nearby, they will cause problems with the bluetooth links. the 2.4Ghz band is a very crowded chunk of spectrum, and also includes microwave ovens. i worked for almost 10 years at a major retailer's service center. out of all the failures of bluetooth audio devices, by far the most common was interference. the system worked fine at the service center, and in the store when the customer picked it up, but when they got home it would fail again. sometimes, the customer could fix the problem by putting the bluetooth receiver closer to the transmitter, or by moving their wifi devices further from the bluetooth equipment. the largest number of interference problems were in apartment complexes, where everybody has wifi, bluetooth devices, microwave ovens, cordless phones, and baby monitors, all of which share the same bit of spectrum. you can do a site survey with a Software Defined Radio that can operate in the 2.4Ghz band (the cheap SDR dongles don't go above 2.0Ghz, so you need to find one that does go to about 2.5Ghz. with that most SDR software can show you the signals present in the 2.4Ghz band, and with some, you can save a plot of the activity in a 24 hour period. that can give you a clue whether all of the bluetooth devices will or will not be interfered with. the only remaining problem is increasing the range by a factor of about 4.5. there may be antenna options (like a "cantenna" to extend the range (highly directional), or passive boosters that increase the antenna "aperture".