Are cables additive or subtractive?

My impression with all cables (including mains) that I have thought an improvement on what I was using previously is that more of the music is getting through to key components of the system, and ultimately to my ears; or to put it another way, the musical signal is being better conveyed. This implies subtraction: the reduction of hash or interference that otherwise impedes musical fidelity – but not necessarily subtraction from 'the signal'. 

Depending on your equipment and the room, cables will make a difference. If you have cheap junk gear, you will most likely not hear any difference. Types and brands all sound different. case in point. Same gear, same room. Speaker cable "A" I already own and happy with. sounds great. Cable  "B" brought over by dealer, $1300.00 cable. Sounds like crap, like wet blankets were put over the speakers. Cable "C" recommended by another dealer. delivered more focus and detail. $1300.00 as well. I own them now. Yes all cables will make a difference as long as you have decent gear top start with.

Who's to really say? Do cables,

• hinder clarity or add shrillness?
• strengthen base or bloat the lower end?
• add warmth or smear the sound?
• tighten and focus or lessen body?

I think one has to be intimately familiar with one's system and proceed from there. The more resolving the system, the easier to discern how (hopefully) the cables get out of the way of what your'e hearing. One must pay attention and rely on that (often derided) auditory memory one has to ensure that what improves isn't at the expense of other qualities that one enjoys or has finally ironed out. 

It's a game (and a gambit) and should be looked at it as such, but in my experience, I want a cable to only subtract the negatives and not add a thing to the mix.

All the best,
Nonoise

Cables can only subtract from the original signal because they are passive devices.

From a purely theoretical perspective, all audio equipment is intended to amplify, pass and reproduce the original signal unaltered.  This is obviously which results in many different approaches to achieving the best final result.

I think that noise elimination is a key.  You can obviously hear noise directly if it's significant enough, but I also think that having noise has a significant impact on the overall sound.

If a cable, for example, results in a more harsh sound, it didn't add the harshness, it either allowed noise into the signal or filtered out something else that left the harshness.

Because every cable will filter out slightly different things and/or allow different levels of noise into the signal they may all sound different.  At this point listener preference takes over and if a cable improves the sound to my ear, I will tend to think of it as additave.

Think about a cup of coffee.  Coffee is the signal and the goal of the water, temperature, process used, etc. is to make the final cup of coffee to the taste of the person drinking it.  Increasing the quality of the water or changing the amount of water used doesn't add anything to the coffee, but does change final taste.