It's nowt to do with ADSL2+ itself; more to do with the BTw WBC that EE resell. It's been 0dB since Orange went WBC 2.5 years ago; before that it was a meaningful value, 18.7 dB say, on Orange LLU ADSL2+.
You may find it does report positive with a diff router, but I doubt it. My Netgear also show it at 0dB.
Another anomoly I find is that it reports it under 'Far End Indicator' yet my Netgear reports it as Down, see:
http://forums.thinkbroadband.com/freeserve/t/3995938... . I thought Down was the 'Near End Indicators'.
@ Any Plusnet user on ADSL2+: Does your Down Power also report 0dB?
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC