That appears to be the case with as many issues being reported.
Don’t get me wrong, I’m not saying the FH5 sounds “better” by describing them like speakers. This is going to be another example of different flavors.
Some quick comparisons now that I have proper Fiio sets. Maybe. 
The FH3 has the most bass, has more recessed mids and treble compared to the other Fiio hybrids. Might be too “fun” for those wanting a balanced listening experience.
The FH5 is the most balanced and natural sounding of the Fiio hybrids. Might sound boring for those wanting a dynamic/energetic replay.
The FH7 has the most treble energy. It’s bass sounds the softest of the Fiio hybrids. Treble detail might be too much for some. Can be sibilant at times.
The FD1 is a dynamic beast and has a very wide sound stage, even compared to the FH3.
