There are no secrets here.
A rather specific programmable Xmos chip is responsible for the conversion to I2S, and qualified development, testing, etc. are needed here. That is, in order for the conversion to I2S to work well, everything that the Chinese cooperative does not have is needed.
They had a normal code for USB, and someone did the rest at random (and this was of course not Topping's cooperative)
The rest is simply impossible to spoil.
Of course, it's possible to make the output amplifier primitive and not how it can be done well (for example, like in this DIY I2S DAC
https://nihtila.com/2020/12/28/w-dac-s-4493/ ). But a decent op amp will save the day.
Of course, a good power supply of this design will cost more than cheap microcircuits, and therefore no one will supply you with good power at such a price.
The conclusion is simple - this is USB DAC, and no more.
This is far from the best USB DAC.
And probably not even very good.
But it costs less than a good USB dongle DAC.