Hi all,
So last night, after doing a disk to disk backup (Swap the disks and I'm back to W7) I had updated to Gloucester BEFORE going to W10. I have a MOTU 2408MK3 on a Intel I7 quad core machine (A proud Studio Cat machine owner here). After Windows 10 came up I was happy to see that my MOTU interface had 'sync'd' up to the 41.1 sample rate I had set it to before the upgrade and I heard sound. ' tried playing an MP3, worked fine. Opened Wavelab, again, worked. Opened SPlatinum, and, after about 30 to 40 seconds, I heard a white noise like sound for a couple of seconds, then it intensifies for another couple seconds (Gets louder) then in another 30, 40 seconds, this cycle repeats.
Checked the driver page at MOTU and I didn't have last years driver (The latest) so I installed, rebooted but it remains in this cycle when I open Sonar. I tried opening X3. It also has the couple of seconds of white noise like SHHHHH but doesn't intensify and also cycles. RATS.
Took two other machines over to W10 last weekend with no problems what so ever (I couldn't believe how smooth an in-place upgrade could go, Microsoft did a fantastic job on this one!) so I was a little surprised to hear this.
Any ideas on this, my friends?

Is this with a PCIe 424 interface? And I assume SONAR is using ASIO driver mode...? I found only a few links related to running MOTU 2408s under Windows 10, but it seemed not to be a problem. I'll be upgrading to Win 10 soon, and will find out for myself. In the mean time I don't really have any bright ideas for you, but if it's working with other apps, it seems there might be something mis-configured in SONAR.
 
I'd start by making sure SONAR is not set to Share Drivers with Other Programs, and would double-check all audio settings, especially Playback and Record Timing masters.
 
FWIW, I don't let Windows use the MOTU. I keep my onboard sound enabled and set as the default audio device for use by Windows and generic multimedia apps. The output of the soundcard goes to an external mixer that lets me hear it through my studio monitors.

Thanks for the reply, Brundlefly. Yes it IS a PCIe 424 interface. I have an Apogee Rosetta 800 hanging off the light pipes and it's the main output and timing in & out interface.  I think it is set to share and the on-board is disabled in the BIOS. It's never given me a problem from XP to XP 64 to Windows 7. I haven't called Cakewalk yet, I'll have a weekday off in a couple weeks and I can get on the horn with MOTU and Cake support. Just wondered if someone here is using W10 & MOTU successfully or if they found a solution. My biggest fear is, now that the 2408's are no longer current, that MOTU isn't gonna write W10 drivers for 'em and I'll have a hunk of metal & wires that doesn't work with the current OS.

More information. Called MOTU, They 'may' be releasing new drivers next week, but, it's not the drivers. I have ARCII and that's what's making most of the sound. Plus my copy of T-Racks Black 76 lost it's auth code. The were two tracks that were contributing to the white noise sound, but I could probably create a new track and copy the wave into it and, after setting the output buss EQ and any thing else, it would probably just fine so I didn't investigate any further. I'll contact those companies support on Monday, but it doesn't seem to be SONAR or MOTU Drivers.

Oh, and thanks to Cakewalk support, they got me starting in the right direction to pinpoint the real culprit. :-)

Good post! I've been really reluctant to update my Windows to 10, which I currently have Win7 Pro. It's been so "Rock Solid" very stable, but with Driver Issue's that I've seen so many people having problems. Cakewalk is superior with there Software, I hope you resolve your Interface issue soon. 

OK, here's the end of the story...
BOTH plugins were from IK Multimedia (ARC2 and that real nice Black 76, compressor of theirs) and I wrote to them last night about the trouble I was having, and they answered, like, at four in the morning. They said, "Please download and install the latest versions and re-authorize," and, after I did the 2nd plugin, the SHHHHHHhhhhh went away.
It was easy.
Thanks again to the Cake Techs who pointed me in the right direction I SO appreciate ya!
And there you have it,