For friends with old-fashioned amplifiers and home theaters, let me recommend the GTMEDIA A6, a miraculous retrofit gadget for your vintage sound systems. This player seamlessly connects to all amplifiers, adding Bluetooth, USB playback, and microphone karaoke functions. Just plug in the power cord and audio cable: one end to the player and the other to your amplifier's audio input port. It's that simple! All amplifier speakers can be upgraded for connection. After powering on, simply open your phone's settings, turn on Bluetooth, and connect to the player. Then, play your favorite songs from your phone's music app. The sound will emanate from your speakers with pristine clarity, matching wired connections perfectly.
In addition to Bluetooth music playback, it also reads from USB drives automatically. Just insert the USB drive, and it will decode the music, even supporting lossless formats. It's incredibly convenient and comes with a complimentary remote control for remote operation. With functions like power on/off, volume control, track selection, and even karaoke singing, thanks to the microphone input and built-in sound card. The remote control also independently adjusts reverb and features a one-touch vocal elimination function, making it incredibly powerful. With independent bass and treble adjustment and a full metal casing, it's truly premium. Plus, it supports downloading a dedicated app on your phone for remote control.