That does not cause any restriction to users of the M-Scaler since most of them will be passing 1FS (Redbook) to 4FS (176.4/192 kHz; the maximum Qobuz currently offers for HD streaming) to this upscaler.
You are right. I hadn't used it for a long while but it turned out to be very useful and it is a high quality converter. I just thought it would be of interest for other Forum members to report my findings. It really pays off to bypass the Amanero USB receiver of the M-Scaler.
I have bypassed the Amanero USB receiver of the M-Scaler with the iFi micro iLink USB to SPDIF converter (see attachments) using one of the BNC inputs of the M-Scaler followed by double BNC connection into my Dave/DC4. The improvement was significant and immediately noticeable. Much cleaner...