Review on 🔊 HiLetgo 3pcs M18 Bluetooth MP3 Audio Receiver Board BLT 4.2 Lossless Decoder Wireless Stereo Sound Module by Brian Gopalan

*TLDR Great product if you want to use a 3.7v battery read the last paragraph! Bought to add Bluetooth to a very nice old portable speaker. Works great but I ended up destroying one of the boards due to lack of documentation. There is no separate documentation and the images here and other online listings do not show what resistor needs to be removed. I made the unfortunate mistake of removing the wrong board and frying one of my boards. The sound quality is very good, not perfect. Very strong Bluetooth connection! I was able to move it around my apartment (about 30 feet + 4 walls) with little to no loss of connectivity. ***For those who want to run this with a 3.7V battery, you will need to remove the SMD resistor that is just behind the "Key" wire connection. If you don't, it turns on normally, but makes an annoying noise every 10 seconds that completely cuts out the audio. If you plan to run it from a 5V supply DO NOT make any modifications, it works right out of the box.