UPDATE: I have been using a newer Denali Limited Edition which was built much more recently. It's now very, very close to the Everest in the main room. I think the newer included circuits have improved things across the board.
Did anyone of you tried a Sigma NR V2 in combination with a AQ Niagara 5000? I heard mixed feedback from not to mix these brands noise reduction systems till good feedback as long as you use the Sigma for components and not as feed into the Niagara.
Of course your comment can be to try it, but just curious if there is some experience here. Thanks.