There doesn't seem much of a market opportunity, and after all, the usual suspects are all made in China anyway. By "not much of a market opportunity", I mean that prices are already low on good stuff.
I have a Presonus Studio 24C that is an average DAC and an average ADC--but that's average compared to high-end commercial ADCs. Average = SINAD in the 95-100 dB range. But what is the point of an ADC with better dynamic range than that? No analog source being digitized is anywhere near that good, even if the recording leaves half a dozen dB empty at the top for later normalization to 0 dB. I paid $130 for that Presonus unit, and it has fairly decent microphone preamps with 50 dB of gain, plus a very good way of mixing recorded tracks with the microphones/line-level inputs into a headphone amp (which is admittedly not powerful enough). It's ideal for laying tracks in a home studio. It also comes with a license to the Presonus DAW software, which seems to be regarded well. That's an awful lot for $130 (yes, it was on sale). And they have a cheaper version that costs $99.
If I'm making needledrops, my cartridge will do well to deliver 70 dB of dynamic range. The phono preamp and tape outputs of my 30-year-old Adcom preamp are well into the 90's in terms of SINAD--so I have plenty of headroom for making needledrops. Any other analog source will be worse. In a well-equipped vintage studio, I might have a better analog source than 70, but it won't be better than the ADC on that Presonus. Even with microphones, it takes a pretty specialized application to be able to use more than 95 dB--peak recorded signals have to be well over a hundred dB SPL at the microphone to be 95 dB over the noise floor of even quiet studios. And people who have quiet studios are not shopping downmarket for electronics. My Benchmark ADC is wasted on that duty, but it sure does make it easy to set the gain and really know what it is.
So, Topping or SMSL making one with 110 dB SINAD on the ADC side (which would make it better than my much pricier Benchmark ADC) would have to find somebody who even thinks they need that. People who record may not all chase specs the way people have been doing with inexpensive DACs. For recording, there are many other features much more important, including gain management, mic preamps, phantom power (which the Presonus has), low latency, clock management, etc. Pros use their DAWs but they also use physical controls on the devices, and those drive up costs, too.
I needed a way to lay tracks on recordings during Covid, and tried to use Behringer analog mixer (which had the needed mic gain and phantom power) into my Benchmark ADC1. But the Behringer mixer had developed a -40 dB 60-cycle hum. The Presonus was what I could get for cheap that let me plug a real microphone into it. And it's really amazingly good--I lay tracks directly into Audacity with it, while listening through headphones plugged into the thing and not a hint of latency. I'm not sure Topping could, um, top that in any meaningful way at a lower price point.
I'll take all that back if Topping or SMSL makes a $75 "sound interface" like the Creative X-fi HD with much better specs and no crapware. That would be cheap enough that one could buy them for lots of low-fi duties like making review videos for YouTube, etc.
Rick "except that nobody is mixing in the analog domain any more" Denney