Thanks
@twister6, makes sense. But isn't this for most part impedance (mis-)matching related? It has been > 30 years since I had my last physics lesson (yes, I am getting old). But if I remember correctly, input impedance (of an IEM/HP in this case) should ideally be > 10 times higher than output impedance of the amplifier. Otherwise you could see the voltage drop/swing. The VE10s have an input impedance of only 8 Ohms; I do not expect the DX340 AMP15 to be specced lower than the required 0.8 Ohm (cannot find this number, though). Was surprised to see similar issues mentioned with Campfire Audio Clara (on my shortlist), as these have an input impedance of 13.3 Ohms.
Btw not saying it is not/cannot be cross-over related.