Need help in trying to trace cause of distortion

Hi rvpiano
 it’s not a simple problem but if you do as someone else suggested, by elimination, you will be successful. My guess is similar to yours, I think it’s the speaker. Luckily, this one is the easiest to eliminate. Check to see if it does it with both. If not, move the speaker cables by swapping left for right. If the problem follows the cable, then you know it’s not the speaker. If the problem stays in that channel now it’s time to move the speakers to see whether the problem will follow the speaker. If it does, then you have your answer: it’s the speaker. If not, now do the same thing with the amps. Swap the input cables. If the problem follows the cable, it’s not the amp, move upstream. Hope that helps. 

RV, I think you are right and spenav 1++ Distortion like this is usually mechanical and the obvious culprit would be the driver that handles the midrange. It would only be in one speaker and just listening to each driver close up should be able to locate it. I assume you only use CDs so forget about miss tracking. I have seen cable connections do funny things, bad plugs or bad solder joints. First is to detect what channel has the problem as it is unlikely that both are doing exactly the same thing. If by chance both channels are involved the only common denominator would be the power supply of one of you electronic devices. If an amplification stage is not getting enough power it will clip early and there is a lot of energy at 1000 Hz but I think you would notice the distortion in loud passages and transients. Good Luck!

Thanks for the tips.

Both my GE Triton Ones an Triton References both play flute fine with zero distortions. 

Download REW  https://www.roomeqwizard.com/ and purchase a calibrated microphone  https://www.parts-express.com/dayton-audio-umm-6-usb-measurement-microphone--390-808

Learn how to use them and you will be able zero in on problems like this in short order.