Like Mark says they just seem better. What is extra special about them is that they have this effect whatever the DSLAM manufacturer is, for a long time we observed that a manufacturers own chipset out performed any other when paired with a matching DSLAM chipset, but the SpeedTouch's seem to work with everything pretty good.

The SnR figure is generated during the negotiations between the modem and router, you see wildly different figures of both line loss and SnR just by swapping modems, so it seems to be heavily dependant on the combination used. What I can tell you for fact is that the speedtouch figures almost always matched the line loss figures generated by my independent tester which could measure loss over a range of frequencies independent of the DSLAM. This is one reason why I have such faith in these modems. I still think the 546 is the best of the bunch

The really strange thing is that lots of Cisco routers also have the same chipset (old Alcatel?) as the Speedtouch, but they perform terribly on even marginal lines. So I think there is a lot done in the firmware version they are running.

Cheers

Cris.