MIT Oracle AC1 with Isotek Sigmas

Will it be too much filter if I used an MIT Oracle AC1 with Isotek Sigmas? I noticed when I hooked up the MIT Oracle AC1 with my dual monoblocks via the Sigmas, the highs became rolled off and constrained. The bass region became particularly deep and fuller though. Could it be that the AC1 still needs breaking in? Any answers will help. Thanks.