Well after a quite successful Cheltenham I went and bought an amp, a FIIO A3 to complement my FIIO X1-2gen. And put into action initially with an ZS10...wow there a pretty distinct improvement, less muddyness in mid range, firmer bass and as if a veil had been removed from the music, it really brought the ZS10 to life.
Today listened to AS10, not so much of an improvement. Seems to me a little brighter, maybe a tighter bass.
Also, used with a set of Motorola over ears and also lifted them to level above what I expected.
Looks like due to its impedance of 32ohms (iirc) the ZS10 needs a bit of Welly behind it to really sing.