Need help in trying to trace cause of distortion

I’m trying to track down the cause of distortion which occurs in the range of about two octaves above middle C (around 1000 hz-1500 hz).  I hear it it the flute most  distinctly but it must also be there in other instruments in that range.  I’d like to determine which component is the culprit.
The equipment is fairly new except for a vintage Conrad-Johnson PV-11 preamp recently examined and Teflon recapped by the manufacturer.  I suspect it is in the GoldenEar Triton 1 speakers.
The amplifier is a Benchmark AHB2. I don’t think the other components would cause this phenomenon, so I won’t list them unless requested.  It occurs no matter what source is playing.
Otherwise the system sounds fine. Does anyone have any suspicion as to what component is causing this so I can take it for repair?