The Audioengine speakers will work fine. Just keep in mind that the volume control of the Senn amp does not affect the XLR or RCA jacks on the back, so volume will have to be controlled by the volume control on the Audioengine speaker.
+1. Same here. I have a large library of classical and jazz 96/24 FLAC and the Leckerton reproduces them beautifully. You can't draw assumptions simply by taking numbers from a spec sheet and plugging them into an equation -- ultimately, you have to listen.