Just a note in case anyone else tries this.
I bought one of these modules on eBay and following some instructions from someone on YouTube, I resoldered the jump link to set the voltage to 5V instead of 3.3V (there are 3 solder pads and you join 2 of them).
I did this because I could not get the module to make any sounds, even though the (busy) LED was flashing as if it was receiving commands etc.
Anyway. Following switching the module to 5V, it still didn't work, but when I tried to re-load the AD4 files, the SD card was no longer readable.
So it looks like the module may work on 5V, but not all SD cards (well not mine).
Hence I'd not advise anyone to try this unless the know their SD card is 5V tolerant.