topping is cheaper, but it also breaks much sooner and it comes with a defect if you bought the first version, guaranteed. If it breaks, doesn't matter much the price how cheap it is. if it breaks ends up very expensive.
Maybe the problem is the owner and not the equipment: if you like that stack, you own it, and you didn't noticed how terrible the knob is, at several levels, maybe you don't judge the equipment as it should be judged. Not to mention when talking topping, it's all new devices. There are people with 5 year old violectric, or chord, or SPL, or sennheiser, or sony, or... Anything topping from 2015 out there still working properly? well... maybe not so many, LOL.
It is what it is.
nocte buna friend!! sell it while it's not too late, just sell it. Cu placere!!