ASIO Driver Selection with Tascam 16x8 affects bit rate support

Cross posting from my learnings that I added to the Tascam forum:

Problem: After seemingly 2 years of flawless operation of Win10 and my 16x8 Audio Interface, I started getting errors when trying to use them with Cakewalk Sonar. Specifically, if I tried to use anything with a 16-bit sample rate, Cakewalk would complain that the device didn't support that depth or was in use by another app.

Troubleshooting: I started with the typical uninstall/reinstall the drivers, but no luck. I then started changing configs in Sonar. I tried changing the default sample rate, experimented with different bit depths (41,100, 48000, 24-bit, 16-bit) etc. Once in a while, things would work. But no working combination would survive a restart of Cakewalk. After every restart, I was back to the errors about rate/depth not supported.

One thing I noticed that was VISIBLY different in the experience was that Cakewalk reported the NAME of the ASIO driver as "US 16x8 Mixing Driver". When things used to work, there was no "Mixing Driver" in the title.

I did a little detective work in the registry to see which ASIO drivers were registered with COM, and sure enough there are two different Tascam drivers registered:

US-16x08ASIO.dll (I'll call this the more compatible driver without the "Mixing Driver" name)
us1608asiodriver_x64.dll (I think the new one with the "Mixing Driver" name)

Next I read the release notes for the 2.X driver. It called out a specific change that got my attention. The notes say that the "Mixing Drive" stuff allows you to play ASIO and WDM at the same time. I think I understand this. In the older configs with the older driver, you could do one OR The other. So for example, if I am running Cakewalk using the ASIO drivers, but I want to switch over to media player and play an existing mp3, it wouldn't work. So this new "Mixing Driver" evidently aims to allow a PC user to do both at the same time. So a good goal.

Unfortunately, I think part of the price there is that it limits the bit depth in some way. So if you have the "Mixing Driver" as your default in Windows (which is a WDM driver selection), it registers the corresponding ASIO "Mixing Driver" driver with COM as the system ASIO driver. And that newer driver limits the bit depths so that they match between ASIO and WDM (maybe to 24 bits).

Solution: To make Cakewalk use the "most compatible" ASIO driver (US-16x08ASIO.dll), you simply have to set your Windows (WDM) default settings to the one without the "Mixing Driver" in the title. If you go to settings, systems, sound and look in the list for something like "Choose your output device", you will see two entries for the 16x08 device. Choose the one that does NOT have the "Mixer" in the title. This should have two results:

1. Cakewalk will use the corresponding ASIO driver for this "more compatible" driver and all your bit depths and sample rates and such will just work out of the box. The driver name in Cakewalk will not have "Mixing Driver" in its name.

2. You will not be able to play through the ASIO driver (from Cakewalk for example) AND also play regular Windows things (like Media player) at the same time. It will be one or the other.

All this based on experimenting and hacking around. Your mileage may vary.

I have the US 1641 which came a few years before the 16x8, they are pretty much the same and might even use the same driver.
I use the driver that came out in Dec of 2014 and have never had any driver issues since then.
It actually works better than my Focusrite 6i6 which I put to one side a year ago.
Tascam drivers were pretty bad when I first got the unit and this was the reason I got fed up and bought the Scarlett. But since that driver update in 2014 I returned to using the Tascam because the pre amps are better. I play movies and use Media player and many different audio applications and never have to make any changes. This might be because I have always stayed with 44.1/24 bit.