I used a module for playing some WAV files via UART. The module was controlled by an Arduino connected to several buttons. There was a delay of around 300-500ms when switching between tracks. The delay persisted when I manually triggered the audio module. The only way to improve its performance was to reduce the sampling rate, so I suppose it's a hardware limitation.
I've heard similar things about the DFPlayer and Adafruit FX Board. I thought the Adafruit FX Board was better, but it had similar issues according to a forum post (https://forums.adafruit.com/viewtopic.php?f=19&p=887011). In fact, I found out that I could improve the current module's performance by reducing the WAV file sampling size, thanks to that post.
Is there any other audio module out there with gapless playback capability for WAV files? Or do I have to use a Raspberry Pi? I have one lying around, but it's somewhat overkill, and the power consumption is not optimal.
I found this one (Tsunami Super WAV Trigger - 25 Voice (Qwiic) - WIG-20636 - SparkFun Electronics), but the price is literally more expensive than a Raspberry Pi, not counting taxes and shipping costs to my country. The Adafruit Wav Shield (Adafruit Wave Shield for Arduino Kit [v1.1] : ID 94 : $22.00 : Adafruit Industries, Unique & fun DIY electronics and kits) is cheaper, but I'm not sure if it's going to outperform their FX Board.