Sony CMT-BX50BT Bluetooth settings for Macbook Pro

Macbook Pro bluetooth connection to my Sony CMT-BX50BT is rubbish - constantly cutting out, changing tone (flat to sharp or vice versa) and dropping connection.  Currently sitting 4-5 metres away from the Macbook Pro. 

Playing with bitbool settings under Bluetooth Explorer (part of Xtools) the following figures seem to be stable at the moment: 

Allow Dynamic Bitpools - yes
Current / initial bitpool - 35
Minimum bitpool - 35 (previously 25)
Maxium bitpool - 40

This can possibly be refined further.  

Anything over Maximum bitpool of 40 seems to cause issues. 

Seems to be related to Wifi Interference? Tried changing wifi channel to 5. Retransmissions has dropped to 1-5% which is great.

Initial bitpool: 31
minimum bitpool: 30
maximum bitpool: 50
Allow dynamic: y

Turning WIfi on causes retransmissions to jump to 80% and total loss of audio. Turning wifi off the problem remains until I disconnect and reconnect bluetooth.

Bitpool rate of 53 is required for 328kb/s at 44.1khz. That's our ideal target.

http://wordpress.anykeycs.com/?page_id=13

There is a table in the A2DP Specification that shows several values to use that result in the following bitrates.

Medium Quality
BitPool=35, SampleRate=44.1khz = 229kb/s
BitPool=33, SampleRate=48khz = 237kb/s

High Quality
BitPool=53, SampleRate=44.1khz = 328kb/s
BitPool=51, SampleRate=48khz = 345kb/s

There are also parameters called “MinBitPool”, “MaxBitPool” so the device can pick for itself depending on mp3 quality etc.

Have been running 10 mins on Bitpool Max 56, min 35 and it's rock steady at 1-2% retransmission.

Turning on Wifi, retransmission immediately jumps up to 50-90% and audio fails.

Also tried adjusting "maximum buffer of" to 120 packets on the theory that a larger buffer will help against drop outs. Of course that's an assumption - I don't actually know what that buffer is for :)