Both and neither! There is absolutely nothing wrong with the summing buss in PT and it certainly stacks up well against most other digital summing busses. Of course some people have opinions on digital summing busses and given the choice I would probably go for the summing buss in a Neve VR series desk! There are issues with sound quality in PT|Mix; conversion, filtering, clocking, etc. But nothing in the real world to worry about with the summing buss.I've heard some people say the mix summing bus in PT is not great.Is there some truth to this or is it just opinion.