coys21’s description is accurate. Transmitting music with Bluetooth sends the music through the Bluetooth transmitter in the phone to the Bluetooth receiver that's part of your system. Bluetooth transmission compresses the signal from its original resolution, whether the music is stored on the phone or retrieved from a music service. There have been advances in Bluetooth quality but it started as a technology to connect keyboards and mice to computers and wasn’t originally designed for music.
When you instead use WiFi from the phone to a "real" streamer, the phone is just a remote control, as coys21 said. The phone tells a music service like Tidal, Amazon HD, etc., to send the music, uncompressed, through your modem and router directly to the receiver at the original resolution provided by the music service.
When you instead use WiFi from the phone to a "real" streamer, the phone is just a remote control, as coys21 said. The phone tells a music service like Tidal, Amazon HD, etc., to send the music, uncompressed, through your modem and router directly to the receiver at the original resolution provided by the music service.