I want to buy some wireless headphones to use with my iPhone. I wouldn't be using them so much in the home, but more for when i'm out on my bike or on the train. My portable bluetooth speaker connects so easily without any external transmitter or power supply necessary. Do wireless headphones work in the same way? I've noticed that many come with a transmitter which you have to plug into whichever device you're sending to the headphones or which you need to plug into a power supply. I'm looking to buy a pair for around £100 (or below). The Sennheiser RS 160's look good enough for my needs but wanted some clarification on the transmitter issue.