Just found this on the Topping website:
D90 MQA version V1.23 firmware update
This firmware is only for D90 MQA version. This firmware fixes the problem of D90 MQA version while playing DSD256 on MAC. If firmware of your D90 MQA version already V1.23, then you needn't do this update. Standard version of D90 do not have this problem so you needn't do this update either.
Please noted that standard version D90 is not able to add MQA support by this firmware, flasing this firmware to standard version of D90 may caused irreversible damage. So if your D90 is a standard version, please DO NOT try this firmware.
The update requires a Windows 10 OS with V4.82 drivers installed. V4.82 drivers could be download
here.
If you have questions about the upgrade of your D90 MQA version, please contact us before updating this firmware.
Download here
Does this address the Issue I mentioned previously, at least for the Topping D90 MQA?
I may have access to a Windows 10 PC, so I was wondering how to update my late 2012 IMac after a firmware update on the Windows 10 PC. If some people do not have access to a Windows 10 PC , then I assumes that their Mac cannot get this firmware update.
Now, regarding the SMSL M400: I am wondering if the same thing has to be done to this DAC, since it has the same XMOS chip, and can this be done with the same firmware update of the Topping D90 MQA. In other words, can we use the same firmware update for the SMSL that is applicable to the Topping?