I took a peek, and it seems that the ones they tried were rknanodB and C, which came at 2013-ish and earlier.
With the original firmware you'll have the first few seconds of every song cut off. The first update corrected that except for the very first song sometimes having the first few seconds cut off. However the updates after the first, yes its a mixed bag, fixes for other things according to the release notes but folder navigation, at least in my opinion, gets worse with every attempt to fix it.
Is the sound comparable between the two?
Each has a bit of a colored sound. After all they're both rather inexpensive. Each a bit different. There's a thread here for the T6 so you can see what others think. I personally own both. The lack of gapless, no support for cue files when the official product description says it supports them, the way the firmware updates have stopped (almost every other week until they got the basics working) just makes me feel more comfortable with the Benjie which also hasn't had firmware updates but things work as expected. The D3 adds a bit of low end to my ear say about middle of the bass around 250 Hz and below. The Benjie seems to fiddle around a bit in the midrange where vocals are but not in a way I dislike. In hand the D3 just feels like a better product but honestly the T6 is well built with a metal case so they're both decently built. If you are a song player, that is use playlists and shuffle exclusively then no gapless isn't a problem. Its just that to me spending the $15-$25 more for the D3 over the T6 isn't the best way to go.
They had a history of poor support with another previous player but at least the X3 got a RockBox port that took care of a majority of issues. With the Nano D3 that's the second model I've been burned on. So much for the with these new models comes a customer support commitment verbiage. Obviously not true. Advertised features not working, folder navigation worse than initially and seemingly no more firmware updates. I'd recommend people spend their money elsewhere on a company that shows more concern for their customers.
I think the D3 is only called a successor based on it being a smaller form factor than the X3 X10 etc, plus it's more affordable than their high end DAPs, given the price I think there are better options out there considering the issues with firmware currently, it's a shame as the sound reviews are excellent.
so the sound signature like i mention before is quiet different then?
now i understand that. i've bought the the D3, defenitely different to X2. both are warm but the vocal isn't as full as X2. less treble but more fun. the most dissaponting part is that people said D3's soundstage is wider. maybe it has nothing to do with "sounds comes from outside of head" thing. it's about openness. i'm confused now.
