With the Qudelix I am afraid that one day their amplifier will no longer work, I have to throw them away because they do not connect to anything else ...
The Quidlex 5K is amazing and would drive either set of cheapish headphones. They have very good customer service. My original ES100 is still going strong. I think it's worth a buy either way for PEQ, Bluetooth and USB DAC capabilities.
I don't tend to buy headphones without replaceable cables/parts in general so the latter choice is better on that front. We're talking less than $50 though which is less of a big deal.
Cool thing is that the QX might end up quite tuneable in the app. Would be pretty cooling to be able to change cross over frequencies etc.