DAP is a very niche market product, we can't create enough demand for semiconductor industry to take us seriously. We have to rely on the technologies and components upstream. For instance, we can't develop new purist DAP if there isn't any new MCU available for that job. We have been using different versions of Ingenic X1000 CPU in many DAPs, the limited processing power has introduced a lot of constraint to our new DAPs. Some of these constraints are acceptable back in 2016 (for examples, maximum song limit in music scan due to limited RAM in CPU) but unacceptable nowadays.
Likewise, if we insist our new DAP to be backward compatible, that means we need to stick with our current dimension/form factor, and limited our new options. For example, AKM has confirmed that AK4497 is gone forever, and AK4499 will be transformed into a dual Chipset solution. If we keep the current form factor, we won't have enough space and can kiss AKM goodbye in next generation product. The physical space limitation is going to be another problem. R2R with a better amplifier and line out? Sorry, not possible within current form factor.
I am not saying Cayin will continue the modular concept in our new mid-tier DAP line up, nothing is finalised at this stage. I just wan to explain to our users that while we have tried our best to remain innovative in past few years, our hands are tied.