That is a good question. I would use safety theory to answer this question. If IT audit reduce the attention of financial auditor, the impact on quality would be unknown. If you use IT audit independently of traditional financial audit and if these two audits do not perfectly overlap in terms of fraud or misbehaviour detection, the effect of IT audit would be positive.
To develop this proposition, if I were you, I would use high reliability theory, normal accident theory and other article in safety sciences.