I have the same issue and that is the reason i registered to this forum.
I bought the audiofuse interface for the reamping feature in the first place and i have two issues - the same insane noise AND even when ignoring the noise the signal that is reamped (either with or without the reamp function turned on on the AUX sends) is NOTHING like the direct signal to the amp from the same guitar.
I have hooked up an amp to a reactive load box, am taking the line out into Audiofuse INPUT 1 for monitoring and i am using INPUT 1 set to INSTRUMENT (Hi-z) for recording of the live guitar. When i send the guitars signal to the AUX (set to reamp) into the amp, the tone is vastly different, not even talking about the noise. I also have a PRO RMP by radial - adding that into the chain removes the noise, but the tone of the instrument is still not anything like it is when directly into the amp.
I wrote to arturia about the noise issue some time ago, the response was swift, but the protocol and checklist they gave me would have taken about 2h to thoroughly check everything off.
Hoping to hear from someone with the same issue and what solved it.
This is a painful issue again because i am trying to capture amps with IK Multimedia ToneX...