If you are patching audio through Cuemix, and also playing back audio to the same outputs from another application, the signals will be summed. You won't see any indication of this overload in DP or AudioDesk, because as far as DP is aware, there is no clipping.

The distortion that results from summing the Cuemix output and DP output is actually not clippping, but is actually called "wrapping". Wrapping sounds a little bit different than clipping. The waveform is not getting a flat-top as it would in a clip. It is actually being shifted to the zero crossing at the point it would exceed the digital limit. To avoid this, you'll need to be careful that the sum of the 2 output sources don't exceed 0. When you are working with a source that was already normalized to take advantage of all the bits, you have little room to add another signal. You'll need to scale the master output of DP, and the master output of Cuemix back to achieve the desired balance.

When in doubt, change your Input Monitoring Mode in DP or Audio Desk to Monitor through Effects instead of Direct Hardware Playthrough. Use a Master Fader in the mixing board to monitor the sum of your overall output.