Looking at the way he balances his speakers I would suspect them. This model has a rising bottom end and a falling top end, both together will make it sound tilted in the favour of a darker sound.
https://www.stereophile.com/images/718TekIMfig3.jpg
Nevertheless, throughout the measuring, the Tekton’s low frequencies sounded rather exaggerated. The tweeter array becomes gradually more directional as the frequency increases, but in a well-controlled manner up to 15kHz, above which the speaker’s output drops very rapidly to the sides of the central tweeter axis.Here’s another frequency graph done on another model, as you can see again, falling HF this time starting at 1.5khz!!
https://i.imgur.com/CvgtJLsh.jpg
Cheers George