babyfaceの実機持ってないからわからんけどこれ系オーディオカードお得意のバッファサイズを絞るとドロップアウトだのが発生しますよの注意書きあるな
実際どの辺で安定するんだろう？

10.3 Known Problems
If a computer does not provide sufficient CPU-power and/or sufficient USB-bus transfer rates,
then drop outs, crackling and noise will appear. Such effects can be avoided by using a higher
buffer setting/latency in the Settings dialog of the Babyface Pro. Furthermore PlugIns should be
deactivated temporarily to make sure they do not cause these problems.
More information can be found in chapter 28.3.