Fosi Audio
Fosi Audio BT20A Bluetooth Amplifier, Mini HiFi Stereo Amp Integrated Receiver for Home Audio Passive Speakers, BT 5.0 Class D 2.0 Channels, 100W x 2 TPA3116 Chip, Treble & Bass Control Knob
Fosi Audio
Fosi Audio T20 Bluetooth Tube Amplifier Stereo Receiver 2 Channel Class D Digital Mini Hi-Fi Power Amp Preamp Compact Integrated Headphone Amplifier for Home Passive Speakers with 6A2 Vacuum Tubes
JOYO
JOYO Bass Guitar Headphone Amp Bassist Pocket Mini Practice Amplifier with Aux in (JA-03B)
Routledge
How Solar Energy Became Cheap: A Model for Low-Carbon Innovation