Having had a chance to listen a bit more now, a few more impressions
JH13 FP - High Gain, EQ off
Quite detailed, open and large soundstage
Not sizzly or sibilant
Bass region lacks weight and slam though and is also a bit woolly
JH16 Non FP - Mid Gain (High seems to muddy the sound a bit and create some mild background hiss)
In comparison to the JH13
Not as detailed or as large a soundstage
Bass is a bit woolly and loose.
I think the limitations of the player are quite noticeable between the two CIEMs.
In comparison, the DX100 works brilliantly with both and I have been very spoilt by it.
However, the DX100 is bigger, heavier and more expensive.
If I hadn't heard the DX100 first, the DX50 is an excellent player in its own right (once the fix the UI bugs)
....now if iBasso can shrink the DX100 into the DX50 chassis....roll on the DX200