Joining in. Just got mine last Thursday. So far, I am very happy with the performance. LDAC is very nice. I am also using it as my DAC for my laptop. Quick feedback on it is that it sounds a lot cleaner than the headphone out of the laptop, with zero hiss in the background and better detail...

@KLS In principle, customs IEMs should provide more isolation than universal IEMs because of its customized fit. You might be turning up your volume higher on the customs because of some other factors that could be related to the driver's sensitivity, impedance, etc. 

I have a similar but more compact solution. FiiO E6 Shure SE215 Generic airline adapter Have you tried plugging in your IEMs directly without the amp? I haven't tried it because I'm afraid that I could wreck my IEMs.

wilzc,   Good to know that your impressions on the Pro900s are the same as mine. I have a prototype Pro900 with a different jack and 3D Flex adapter (yellow instead of red/blue) which I have been using since May. I really love its sound and the fit for me is snug yet comfortable.