Integrated amp: jumpers versus cables

You'll never know til you hear for yourself.

I would trust the Manufacturer's judgement.
Cheers

My brother has NAD that originally had factory jumpers made of "U" shape steel rods. Replacing them with short Audioquest jumpers (basically short IC) opened treble.

I assume we're talking about the jumpers in the pre out/main in section of an integrated amp and not the jumpers on a bi-wire speakers.

If they are designed as kind of an on/off switch to merge the amp and preamp sections together, then how does it affect the sound whether or not you have an IC or jumpers?

What about the integrated amps that work without any ic's or jumpers in their path? Are they inherently better sonically because they operate without any jumpers?