Measures with very big 3rd harmonic and bigger 2nd than with cheap Ferrite Inductors :(
When removed I plate "I", distortions became as with ferrite/air, but inductance has fallen almost in 3 times.
I do not recommend this inductors in Hi-Fi Loudspeakers.
You can see my THD measurements on 2x26W/4867 in this link https://cloud.mail.ru/public/23VP/2PWf2v4Se
6.8mH was measured with 2.83V; other measurements with 8V RMS in same conditions.