What have I done? I've been capturing analogue video via Firewire using my Z1 to transcode. I'm now getting an audio echo on playback from the timeline. No echo with WMP.
What setting have I accidently changed in Vegas (6d)?
Are you also playing back thru your Z1 when playing back from the timeline? If so, that will cause an echo, since the data moving along the firewire connection from the PC to the Z1 will have a slight delay as compared to your sound card on the PC.