iFi Audio GO blu Review: This Elegant $200 Bluetooth Headphone Amplifier Is Powerful & Compact! - HIFI Trends
Audiolab M-DAC Mini Portable DAC Bluetooth Headphone Amplifier – Digitalis Direct | The AV and Hi-Fi Specialists
NEXUM Aqua+ Bluetooth Headphone Amplifier
Amazon.com: Auris Amplify Portable Hi-Fi Bluetooth Adapter Receiver for Headphone Amplifier with 32bit DAC Amp, LDAC, aptX HD, aptX, AAC, Clip and 3.5mm AUX Output, Black : Electronics