Why did you install ASIO4ALL at all ? I think its good that you deinstalled it,
as using ASIO4ALL is IMHO
- not a good thing and
- not "best practises" to build a reliable and professional solution.
The rationale behind ASIO is, that you have an highly optimized audio driver between DAW and your audio hardware with nothing disturbing in between. And under Windows a true ASIO driver like the RME one bypasses i.e. completely the Windows Sound system which is a good thing, as in the windows sound system you have a quality degradation of audio data and increased latencies, etc ...
But ASIO4ALL is an additional layer between the application (DAW) and ASIO and WDM drivers.
ASIO4ALL only became kind of "famous" as kind of a workaround for some folks...
As a DAW can only work with one audio driver this enables you to
- to use an ASIO driver and multiple USB based micros
- different ASIO drivers or
- both in combination
But its an additional layer, which
- adds kind of complexity
- most likely adds latencies
- most likely results in audio data not arriving at the same time in the DAW (as i.e. an USB mic can't be clock synched to other audio interfaces
- results in potentially less quality as the windows sound system is being used along with WDM AFAIR
So ASIO4ALL I personally regard as a "workaround", if somebody did not do a proper planning/design, what recording interface he requires. Its not a professional solution, I would expect a quality degration, but some people are happy with it when it works, as it safes them some money, instead of having to upgrade their solution...
The far better solution is to get the recording interface which satisfies your demands in terms of the amount of required channels.
Or - what is possible with RME and what you did now and should do - to stack up to 2 or 3 of the same recording interface (see manual if and how many RME interfaces in parallel are possible) and leave out ASIO4ALL.
To put another example what could be done nowadays: RMEs new MADIface driver enables me for example to operate 2 UFX+ and an ADI-2 Pro in parallel. As all these interfaces use the same MADIface driver. So when I select in the DAW (i.e. Cubase) the RME MADIface driver, then I have direct access to all the channels of the 3 audio interfaces. They need to have then the same ASIO buffersize configured (easy to do) and of course need to be clock synchronized (I did this by using ADAT and AES channels, WC is not required).
BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13