Does anyone know if you can connect Bluetooth headphones before I go buy a pair
At this time No there is not a way of connecting Bluetooth Headphones to the Code.
You can use bluetooth headphones by using a bluetooth transmitter pluggd into the headphone jack on the amp. I have tested this with a standard bluetooth audio jack transmitter (about £12-£30 online). However the latency with the cheaper transmitters is not useable, it's about 05 seconds. However there is a new type of transmitter with a technology called Aptx, this has a standard latency of <100ms and with can be as low as <35ms if the transmitter and receiver use Aptx.
I will hopefully be getting Aptx headphones and a transmitter shortly. I will update here when I do, or if anyone else is trying this I'd be very interested to hear about results and devices used.