Hi Garry,

the fact that the old HDSP driver enabled all WDM devices by default was a major pain in the ass for any power user that had more than one audio interface running and repeatedly tried to change sample rates. For many years we waited for Microsoft to fix it, but they failed and never got it working as it should. The issue: The Audio Endpoint Builder walks through ANY active and inactive (!) device and related registry entry whenever a state change occurs. You can see this as one CPU core completely blocked for some time by the svchost.exe process. In more cluttered states it even blocks the whole Printer & Scanner dialog (which searches on new devices on start). Also the Sound dialog does not open immediately but takes up to minutes (!) to open.

The first step to get the computer to react quickly again is to remove all currently inactive devices. That helped for some time, especially with USB interfaces, and is still a good tip. But the final solution is to remove all and any entry in the registry under Capture and Render of

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\MMDevices\Audio\

The problem here is that you are not allowed to do so. It takes some guts to get the rights and work in that area - nothing we could explain or recommend to our customers. And this looks even more stupid as once you do so you notice that these are all Plug & Play entries - whatever you delete will come back the next start, but only the currently active devices, so the lists can shrink from hundreds of entries to below 20. Blocking this part of the reg against manual deletion doesn't make any sense IMHO.

To summarize again: The Audio Endpoint Builder checks and tries to access not existing hardware, and it gets stuck by using Registry entries from not existing audio inputs and outputs. This is a serious design flaw since at least Windows 7 (most probably Vista as well). There exist no tools that could delete these Capture and Render entries, nor do they ever get deleted. Manual deletion requires complicated and dangerous mangling of rights and editing the registry. This is a very unfortunate state. And no one except Microsoft could change that.

When Windows 10 came out we first thought it worked better, but in reality our systems were just fresh.