Just sharing some comments on these:

Been using the DFPlayer for years on many projects and it fundamentally works.

Am putting a project in a dune buggy, where it will get shaken and vibrated A LOT, so was a little worried about the mechanical stability of the SD-Card connection on the DFPlayer…. and I liked that both the DFR0534 and the DFR0768 have on-board soldered-in file-space that would be largely immune to shake/vibe.

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So I've been using the DFR0534 and generally like it and it works. A couple issues:

1) limited memory for sound files (6mb) so only applicable for short sounds. This is ok for my dune buggy project though

2) I want minimal time lapse between one sound ending and starting the next sound, and what I've found is that when the DFR0534 has sat idle for a while, then you start a sound, the BUSY line goes active and sound starts coming out, within about 60ms. This seems long (what is it doing for 60ms!!) but works for me. But if you are playing a sound, and it ends (BUSY goes inactive) and you quickly send a command to start a new sound, the delay can be as much as 500ms. What in the world is going on??! So this causes a relatively large gap between what I want to be back-to-back sounds. Not as good a s the DFPlayer does….

3) The on-board amplifier is a little wimpy…. sound files at max volume aren't all that loud…. the DFR0768 has a much better amplifier for volume. I haven't yet compared it to the original DFPlayer though.

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I was all excited about the DFR0768 “Pro” because of 128mb storage w/o an SD-card, smaller size, better amp…. but it has a FATAL flaw for most of my projects. There is NO WAY to accurately determine when the sound is done playing - no BUSY output, and it's not serial-port queryable for accurate status! Users mention that you can query it for ‘duration of current file’ and then query it for ‘time in current file play’ and compare the two to determine when done, but the responses to these queries are integer-seconds, so you can be off by a whole second in determining when done! USELESS for trying to seamlessly start a file immediately after the prior one is done…. like can be done with the DFPlayer.

So I think the DFR0768 designers really ‘missed the boat’ by not including a BUSY output, and not designing the serial-port queries such that you can accurately determine when the current sound is done…. for me, it's a showstopper and I've dropped any thoughts of using this device.

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So I'm back to using the DFPlayer and hoping that it's SD-card connection won't go intermittent under dune buggy shake and vibe!

Hope this helps anybody trying to decide which one to use.