What's the recording and music? In my experience all Harbeth don't show a sharp piecing treble, even if you use the brightest amp, electronics or cables. Hence I am suspecting the music or recording to be the culprit to the bright sound you are getting with the C7ES3 40th Anniversary. Perhaps the 40th anniversary was tuned to have a treble peak, that I'm not sure but the original C7ES3 actually sounds a bit warm to my ears when compared to SHL5+.
sharp and piercing high pitch /frequency coming out from Harbeth C7
I have a problem with the sharp and piercing high pitch coming out from the C7 40th anniversary speakers when sometimes listening to the soprano or complicated loud passage in CDs. I changed the speaker cables from Analysis Plus Oval 12 to Transparent Musicwave which has a filter for frequency. It got better but not totally elimiated. Any solution for this ?Thank you!