Those black boxes degrade sound?

Those "black" boxes on cables are usually low pass filters, cut off above 20KHz. They probably do not degrade the sound, if you only listen to CD playback, and not analog MC cartridges. But are they needed? I do not think so!

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).

VooDoo "Fixing" the phase after the fact? and exactly how do these boxes decide how much out the phase was. or is? out of wack.
I'll keep it as is. I have not heard the current crop of these things, but did hear another one no longer manufactured, and it was not very helpful.
IE: the sound was btter without the boxes, all else being equal. Now that was to my ears... some folks liked the smeared sound.

Smeared sound? I haven't heard the older generations, but MIT's newer ones do exactly the opposite. Cleaner, more articulate bass, better coherency top to bottom, better defined images, and a larger soundstage.

For image/soundstage freaks like me, check out MIT's MA series, it's a substantial difference over non-networked cables and even their standard lines.

They are not fixing anything other than phase differences introduced by the cables themsleves - that's how the manufacturer decides how much adjusting to put into the boxes. At least that's what the marketing hype says. I have heard legend that the cables sound better if you cut the boxes off, but I don't know who has actually had the chutzpah to cut up a set of very expensive cables for this purpose. Elizabeth - are you saying that you actually heard this done, with an identical pair of cables? What cables were they?
I do know that systems I have heard with MIT cables sound anything but smeared.