klipsch heresy III is a 99 db sensitivity speaker, hmmm, are you listening very close, ie a few feet away?
You might be hearing the even order harmonic of IDA-8.
You didn't say whether this is the first time you got the IDA-8 or speaker, did the noise develop after a while, or it is there from day one?
Try a different speaker to compare.
Regardless, you should create a help desk ticket and contact support to continue with the diagnostic. This discussion is beneficial to other users but not under this topic, which is for AC-4 product.