That figure would mean something if you where switching to another adsl service but not cable as it works differently. Adsl depends on line length so that number matters but virgin have repeaters at the cabinets of each street which supply enough power down the line for the end house to be in the optimum power levels and any house nearer will see an increased power level and thus have to have a attenuator fitted to reduce this. Cable also runs on a completely different network to adsl.
Read the OP please. Thanks...