Is the Pleiades linoleum Auratone type C a failure?

At your risk. Possibly. It turns out the Tesla fullrage speaker used has very little bass, ie high reasonant frequency. But it can be greatly improved by adding in series an inductance of 24mH to remove mid, mid high heaviness, and say 50ohms in parallel with said inductance in order to remove resultant prominance in bass ie add back the sparcle. Fed by the Pleiades 2n3053 class A amplifier when at a high volume setting the non linear distortion on voices, Barbara Streisamd, Bary Gibb is very interesting, on the song What Kind of Fool.