These questions are about the "whisperers" or devices used to hear your guide during RS tours. They are great; indispensable!
Have they gone Bluetooth, allowing non-wired connection to personal ear buds?
If not, can any ear buds / headphones be plugged into the receiver provided by RS?
Is it possible to plug a transmitter into the receiver provided by RS? If so, it could use Bluetooth to communicate with your earbuds, while the receiver could be in your backpack? Any issues, for example, the insufficient volume?