Slower DSL speed after splice

[apgcases]

I have ATT DSL Extreme service and I actually get about 8.0 service. There is a POTS splitter in my box that splits this line out to my office about 75 feet away. I recently moved the office back into the main residence and rather than move the 8 pair wire ATT put in, I jumped it with a new wire back to my new office. At the POTS, I didn't see where I could add a line so I spliced the pair I needed. Now it essentially feeds either building. But, now my speed tops out at just over 7.0. I have to believe the splice affected the speed but I don't understand why. Any thoughts?

 

[hang-the-9]

Quality of the cables. DSL will run slower on lines with interface. I've seen it max out at almost dial-up speeds with old buildings.