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?
128x128rvpiano
RV, to add to the good suggestions above I'll mention that one thing I've found to be very useful in diagnosing sonic anomalies, as well as determining if it is the recording or the system that is responsible for them, is to have a headphone and headphone amp in my system.

In normal use a headphone amp would be connected to a tape output of your preamp, which would exclude the power amp, the speakers, the room, and most of the preamp circuitry from contributing to what you are hearing. For experimental purposes, though, it could also be connected to the preamp's main outputs, or to the output of a source component, or even (using a speaker-level to line-level converter) to the power amp outputs.

A good low priced headphone I can recommend based on personal experience is the Audio-Technica ATH-M50x ($149 at B&H). I have no specific recommendations for a headphone amp, though. (I use Stax electrostatic phones in my main system, which require specialized amplification that is not suitable for conventional dynamic headphones).

Good luck. Best regards,
-- Al

I second starting with headphones for troubleshooting  That is my first goto.
If you have none I recommend 7506's
https://www.amazon.com/Sony-MDR7506-Professional-Diaphragm-Headphone/dp/B000AJIF4E/ref=sr_1_1?keywor...
Not great for extended listening (bright) but good analytical monitors.
However not recommended for dry environments.  They will static zap your ears. I switched to Focal Listen for recording after 25 years of anti-static spray in the winter.
A good enough complimentary amp is
https://www.amazon.com/Nobsound-NS-08E-Integrated-Amplifier-Headphone/dp/B014FASL1A/ref=sr_1_3?keywo...
It sounds better than my Topping TP21 and Schiit Magni 2.
Especially if you roll the tubes.
The whole sets you back $150.

Does this distortion come from one speaker or both? This would be a good starting point.
What makes this problem hard to pin down is that I’ve heard it while streaming a few times and stupidly don’t remember where.  I’m going to have to check through what I’ve streamed to find it.