EDIT: Btw one for everyone, but bumped into this thread last night on r/headphones -
Meet the holy trinity of my broken DX5 II - which is one user's experience of being unlucky with three Topping DX5 II units and them all being faulty. But if you read the link to the ASR forum it seems there is quite a few users reporting problems with the 4.4mm balanced out of the Topping DX5 II. Including
another poor user where the DX5 blew three of his headphones left drivers out (Topping to their credit are repairing said headphones) but its got quite a few people thinking there is a problem with the early ones and/or not having overload protection in certain scenarios; i.e. two headphones connected.
I know we have a couple of DX5 II's on the forum so wanted to link to - in case of interest. Again like all these things hard to know if a this is an isolated few examples, or a wider-design issue (*cough*...Xbox 360 RROD). Although likely most of the time the former is true. But it made for scary reading that a DAC/AMP can nuke a pair of headphones like that.