The sound card and driver would not be relevant in this case. More likely, there is a plugin in the chain that can't handle fast bounce. I have several of those (and one plugin that can't handle a slow bounce, just to complicate things further).
You may be able to alleviate the problem by increasing the BounceBufSizeMsec aud.ini setting. There was a bug in the initial release of X1 that resulted in this value being set to 30, which is way too small. Although fixed in X1a, you could still have that value in aud.ini. Try setting it to zero first, then if that doesn't work try setting it to 350.