IPhone Wifi and Bluetooth interference when used simultaneously

Question

I am presently using AirFoiI to stream audio from my PC to my iPhone. AirFoil uses the same protocols as AirPlay. AirFoil/AirPlay streams an Alac audio codec using a bandwith of 1,50 Mbs on average irrespective of the audio codec and bit rate of the source file.
The audio stream received on my iPhone through WiFi is send over simultaneously to my Bluetooth speaker.
When using AirFoil/AirPlay, I regularly hear distortions at the beginning of a track and also randomly when a track is playing. The distortions are a lot more when I move the iPhone around.  I am almost 100% sure that these sound distortions are because of Bluetooth interference on the iPhone itself when simultaneously receiving an audio stream from AirFoil/AirPlay and sending an audio stream over bluetooth to my speaker.
I also have done some tests using "Net Meter" and "TCP-view" from Sysinternals on my Windows 7 PC.  On "Net Meter" I have never seen any WiFi drop outs or distortions regarding my home network.
My bluetooth speaker supports the A2DP AAC audio codec. This was an important feature for me before I bought the device because the AAC audio codec provides normally a relatively good audio quality over Bluetooth. At the time it did not occur to me that there might be a possible Bluetooth interference coming from my iPhone itself. I presumed that the Bluetooth on the iPhone would use a 2,4 Ghz RF channel not in use by WiFi so that WiFi and Bluetooth used on the same device simultaneously could never distort each other. I was clearly wrong.  Put shortly, the problems I encounter are presumably solely caused by the firmware/software on my iPhone. I hope this will eventually be resolved with some future iOs 8 updates. There were indeed many people having Bluetooth issues since iOs 8.
I know the best solution would be to wire my speaker optically with an AirPort Express or an Apple TV.  I have not yet decided between the two.
Even when there exists a "wired" solution, I think an expensive device such as an iPhone should be able to make sure that there is never interference between WiFi and Bluetooth when used simultaneously on the SAME device/iPhone.  
I hope that some specialists will give their views on my "nonprofessional" analysis and some more in-depth information.

Answer 1

Now will this work:
Airport extreme set to BOTH frequencies and my older wifi stuff like Iphone and printer will automatically connect via 2.4GHz and Macbook will connect to 5GHz so that it will not longe be disruppted by bluetooth?
Unfortunately, no one can predict exactly what will happen in advance with wireless and interference issues. Your chances will improve, though. It might be a good idea to understand the store's return policy before you buy.
What if the Macbook will not connect automatically to the 5Ghz network because the 2.4 stream may be slightly stronger. Is there a way to force macbook to connect to 5Ghz?
Yes, use the option to assign a separate wireless network name to the 5 GHz band, and then "point" your MacBook to that network.  The other 2.4 GHz devices will connect to the 2.4 GHz band.