The top ranking Topping L30 Headphone Amp fried a few users headphones leaving them permanently damaged. That is a huge flaw in my book and it underscores that SINAD performance is but one metric of engineering. It was an eye opening moment for me and I own Topping gear.
If you stay in this forum long enough, you would know Topping DX3 Pro wined the highest recommendation from amirm (which I believe is super double standard, especially in its linearity test) at that time. There was a design issue which would make the circuit become unstable and fail. A lot of user complained about their device burned out their headphones and so on, and more users reported they have a dead unit after a few weeks of usage. Topping never apologized for this, and never did a recall like they did for L30 this time. A lot of users requested amir to put a warning in his review, but he refused to do so.
Even without such disaster, Topping DX3 Pro can never be regarded as a good product --- it has relay clicks whenever you pause your music or switch tracks, and the firmware is very unreliable in that it would go silent in the middle of a track.
I previously owned the O2+ODAC combo, which works very, very reliably. I sold my O2+ODAC and bought Topping DX3 Pro when I saw the good Topping DX3 Pro reviews on this site and--- It just beat my old combo in every way! Turned out that is the worst decision I've made. Had this site not existed, I'd still enjoy my O2+ODAC combo today.