HuoYuanJia
Previously known as Ultrazino
Member of the Trade: HEDD Audio
ZX300 has which output impedance? 2.5 ohms? Running balanced would give you 5 ohms. My iPhone measures 6 ohms output impedance. You can see what happens with the Andros in regards to OI here: http://headflux.de/campfire-audio-andromeda/using Sony zx300 balanced, iphone with DF Red and direct from iphone
They become much brighter and the treble peak shoots through the roof. This could be what you are experiencing.
I suggest to try the same pair with a source that has the lowest OI you can find. And stick to single-ended with the stock cable. (Just to confirm.)
But if you like the VE8, SD-5 will be closer to that experience.