T1? or S1?
If it is for the T1, is it with the Pioneer Edition of Traktor, or Pro 2?
And lastly if it is a T1, which effect does this occur with? For Traktor in chained mode, certain effects use a filter element within the parameters that you can't modify, that will increase with the application of the effect. This can cause a loss in output level. In advanced mode you can control this yourself as a parameter of certain effects.
For example; with a delay, in advanced mode you can modify 3 different parameters, Filter, Feedback, and Rate (or time). Increasing the filter will decrease the output level as you increase the application of the effect. I can only imagine that this is true also when in chained mode. Someone please correct me if I am wrong.