Wireless Expansion Adaptor The Bluetooth® Audio MIDI Dual Adaptor (BT-DUAL) is a compact adaptor that brings Bluetooth audio and MIDI capabilities to compatible BOSS products. Once installed, you can pair with a Bluetooth device such as smartphone or tablet and communicate wirelessly with the product. The actual wireless functionality that's available depends on the specific product model, but may include music streaming with Bluetooth audio, controlling various product functions with Bluetooth MIDI, and more.