I've finally got the C10100E Central Splitter (from MATS Systems) installed, and I'm pleased to see that the new connection speed is a reasonable amount faster than previously recorded. This also means that I've been able to relocate the modem and VoIP hardware into the storeroom (instead of sitting on the kitchen bench!)

ADSL2+ (After Central Splitter) | | Upstream | Downstream | | — | — | — | | SNR Margin | 9.0 dB | 8.5 dB | | Line Attenuation | 22.5 dB | 33.5 dB | | Speed | 942,200 | 12,129,800 |