Why, might I ask? I heard the D70S was great.
There's nothing can be compared to RME ADI-2 series in the HiFi market. No single product has that unique feature set. It's also at same price tag as premium topping a90+d90 stacks. Moreover, RME keeps supporting their products for a long time. You still get the same software updates (which contain many bug fixes and tons of feature additions) as the the newest devices even if you bought the first generation machine back in 2016. Even Apple do not support their devices that long.
Chinese HiFi products certainly lacks the maturity and technology compared to professional audio manufactures such as RME, UA or Apogee. No I'm not bashing on the former but this is just simple fact. They can't even write their own firmware and drivers, not to say FPGA programming that do fancy DSPs. They just quickly release one product after another, without even taking the time to fix hardware and software bugs in last generations. RME is way more experienced and professional in audio design than Topping --- Topping only learned how to design a headphone amp properly after
@JohnYang1997 joined last year. But since the first generation device in 2016, RME ADI-2 series' headphone amp has been based on the same composite topology (or NFCA in Topping's term) that everyone started to know and get fascinated about in this forum just recently. RME just never brag about this technology --- they don't need to. Their product just works.
If you want to try out new devices all the time, Chinese Hifi products are good choice. You buy them, play with them, and sell them in second hand market after a few month, and try another. Wonderful. There are always unpolished rough edges and bugs that never got fixed so you can never continue using it for years. If you want to have a device that just works, close to bug-free, and have long time support, RME is the only option here.
The only downside I see from RME is the cost to fix broken devices is pretty high. Most of the time they just do full motherboard replacement. super expensive. In ADI-2 series, there are a few known quality issues that some people run into, such as opamp burns out or volume knob aging . I am a heavy user so I experienced both of them. With that said, the ADI-2 product line is still much, much more reliable than Chinese Hifi products.