I don't understand why people think Aiyima or Fosi is more trustworthy than Topping. Topping's PA5 was a flaw, but that can't be a reason to give credit to Aiyima or Fosi.
Topping has been successfully provided in-China repair service throughout the past, they give a reasonable customer service, and their products do not seem to show how failure rate except for PA5. Maybe people's complaint is about their price tag?
Many Aiyima's products showed channel imbalance problem, and Fosi used to write their product's spec as 300W+300W while providing a 32V 5A power adapter.(tb10d)
My point is that in order to determine the credibility of a company, you need to do objective research over a long period of time and across many products. Which is impossible for a small company with a short history. Then at best you can only have confidence in a company if they guarantee adequate post-sales support (and I haven't seen Aiyima or Fosi do that).
Topping's flagship LA90 and LA90D (Discrete) both had significant rates of failure, many more with the latter. The LA90D in particular was probably one of the first sub $1k ultra high quality and relatively high power monoblock (bridgeable from stereo) capable amps and many considered it an endgame amp based on performance. I had planned to buy one and figure out if I needed the power output to buy a second down the line. By the time many readers here were ready to pull the trigger, the early adopters were already reporting issues including potentially speaker destroying static and squeal output.
Teardowns of Topping PA5s showed that they died due to taking a very nice custom discrete amp in place of the typical NE5532s op amp stage and coating it with conformal coating and a lid to the point that it overheated in a just plain dumb and failed attempt to prevent the topology from being copied.
And then there is the hassle that Topping availability in North America and Europe is all over the place and through Shenzen Audio, KGUSS (Amazon), and other sellers with variable return and RMA policies. At $800 for an LA90D, consumers want to buy direct from the manufacturer* and in some cases get RMA cross-shipping or at the very least, fast RMA service with paid shipping, not months without product after having to foot shipping bills. (*or a vendor with proper support)
All of that said, I like Topping and may revisit their products in the future, but you can't fault people from being reluctant with close enough offerings more widely available and better reliability and service history. A pair of LA90Ds would be my endgame best bang for the buck amp setup for stereo, though that lead is narrowing.
Failures are far less tolerated than spec sheets we know will have some fibbing. Spec sheet liberties can be resolved by waiting for a competent review like Amirs' here and managing one's own expectations. Burned out bricks cannot be resolved so directly.