Paraphrased from the Wavelab Help File, a DC offset is when there is too large a DC (direct current) component in an audio recording. If the DC offset is really bad, it can be visible as the signal not being visually centered around the "zero level axis". However, the DC offset can be significant without actually being seen. DC Offset almost never happens in the purely analog domain, but occurs quite offten in the digital world. The cause of this offset is the different DC currents present in different digital processors. I have been going through all my wavs and eliminating the dc offset (by selecting the entire wav in Wavelab and then selecting Process|Eliminiate DC Offset, then Oking at the prompt). My offsets were anywhere between -0.075% left and right to 2.6/3.5% left/right. Removing this offset improved my headroom, and in some cases even made my recordings sound crisper and louder.