stepd

That's actually not true in the case of the M2 driver. I can even record in multiple apps simultaneously. I can hit record in Cake and hit record in S1, start playing my guitar, and it will record in both. It's kind of a ridiculously good driver.

Duh (kidding). I'm just saying the message wording doesn't make sense, but the armed track may have triggered the wording. Programming "logic."

Could be an issue with anti-virus software. Here's a thread on the old SONAR forum: http://forum.cakewalk.com/Unable-to-create-new-audio-file-for-recording-m3746652.aspx You're only hitting play but you have a track armed for recording, so that might account for the wording of the message.

You set the driver mode in cakewalk. Press "p" with cakewalk open, click Playback and Recording in left pane and switch Driver Mode to ASIO. Change buffer size in the ASIO panel under the Driver Settings tab in the left pane. I would definitely use ASIO over any other mode. EDIT: Missed the part where you said you already tried other modes, although I'm not really sure if you're talking about the MOTU or the amp output. Does the amp show up as its own input?

But definitely don't skip the step of temporarily disabling it in device manager. You're looking for a possible driver conflict. The MOTU is actually excellent at sharing audio with the OS and has a loopback feature that enables any sound from Windows to show up as an input in DAWs.

A few things to try: Rename your aud.ini file and let cakewalk recreate it. Try a different USB port (unless you're already using USB-C with the MOTU and USB-A with the other interface). If you have onboard audio like Realtek enabled, try temporarily disabling it.

Here's another long shot: Check your CPU temperature (or graphics card temp). I have to blast dust out of my CPU fan every several months or the fan bogs down. The CPU starts runing too hot in a demanding app like Cake, and audio starts to crackle. Audio is generally fine for less intense tasks like streaming video, etc. The crackling also gets gradually worse over time. So it may not be your problem, but it's worth looking into, because it took me a while to figure that one out. Some locations are dustier than others.