I think that probably is the case. With the Elac you can basically draw a straight line through the response all the way to 80 Hz, with the ZA5.2 only down to 120ish. That'll result in a pretty significantly different tonal balance between the two if compared side by side out in the open.Is this really all down to the main obvious difference between the speakers - i.e. the fuller/riper bass response in the Elac vs the muted response in the ZA5.2 making the initial subjective impression so different?
If placed close to a wall with the bass EQed for both, I suspect most of that difference would go away, at least at moderate volumes.