Those DFPlayer modules are superb. I can't recommend them highly enough. With an inbuilt power amplifier of very good quality or pre-amp level outputs they are easy to connect to either loudspeakers directly or to existing amplifiers.
I'm sure I posted in a thread elsewhere how I interfaced them to an external USB socket/memory stick?
I'd been trying to use a unit from VLSI, which I had working programatically. Sadly, I really needed external access to the memory device. As the VLSI only offered built in microSD, I was in the process of re-drawing the circuit and PCB for the module when I had the DFPlayer module pointed out to me. Built in microSD and support for external USB. Just what I needed.
