Cubase is still by far the worst professional DAW in terms of sample rate conversion. For comparison see: http://src.infinitewave.ca
Evertime you import or export audio material (actually up- or downsample) to different sample rates (e.g. from 44.1 kHz to 48 kHz or from 96 kHz to 44 kHz and so on) Cubase introduces aliasing which can reach the audible range depending on your source material / processing.
I am deeply grieved that the SRC hasn’t been improved for over 10 years now.
As WaveLab 9 recently got the artifact free SoX-Resampler, I urge you to integrate the same library into Cubase for up- and downsampling (for the MediaBay as well as import / export). http://sox.sourceforge.net/SoX/Resampling
Further Reading: Q. What’s the best way to downsample?