Those black boxes degrade sound?

MIT and Transparent cables "boxes" contain passive componentry which linearises transit time, such that all frequencies are theoretically in phase at the load end of the cable. Far from degrading your sound the networks are installed to enhance the listening experience --- eh? No they do not wear out, although they can be damaged via inappropriate usage or application of breakin boxes incorporating excess voltages or a DC component.
These networks are not just there for decorative purposes, and if they were't needed, they wouldn't even be there now would they? (indeed an absurdly speculative statement from the uninformed).

as per usual, spouting off again about nothing which BTW "I have not heard"

tell us all, dear voodoo, how good that group delay sounds compared to your smearing reference standard