Wavelab output distorts when Cubase is playing back

Hi guys,

I am running Cubase 7.5 and Wavelab 8 on my Windows 7 PC, using an RME PCIe card with Total Mix FX and I just ran into a problem:

Cubase and Wavelab both work fine for themselves. If I open both simultaneously and want to play back tracks in both programmes at the same time, the output of Wavelab is entirely distorted - it is like a feedback that becomes louder and louder and you can hear a part of the song looped. Cubase works fine (I am using a monitor controller to switch between Cubase and Wavelab). The ASIO outputs are on different MADI streams obviously so there cannot be a feedback from within TotalMix. This is quite annoying since I would like to use to compare mixes with references for example or simply record from Cubase into Wavelab.
Even if the playback in Cubase and/or Wavelab is stopped you still get the “feedback”. In TotalMix you can see how the Wavelab output is stuck and only closing one of the programmes stops it immediately. Wavelab doesnt show anything suspicious, it just works normally and displays a normal output.

I thought switching Wavelab to a MME driver would solve the problem but it doesnt, as soon as Cubase is playing back there is no sound (or something that may be considered fractions of audio) from Wavelab.

Any suggestions? Working this way seems impossible.

Btw - i managed to eventually find the ticked box which was responsible for the phenomenon (DSP settings of my RME card). It is called something like ‘optimise for multi client operation’, along those lines anyway. Perhaps this is helpful to anyone.