Old setup was as follows: Lenovo W520 connected to TV using a passive DP to HDMI adapter. Audio was fed from the TV to the Harman Kardon receiver with digital coax. Audio worked fine, no delays. Then ...
I have an older Panasonic TC P50ST30 (release review/specs here) that was generously given to be by another Arsian that does have ARC support (I think). The TV sitting in front of an old but nicer ...