Amongst audiophiles there is a common school of thought which says that signal paths only add distortion and noise and degrade performance and as such should be kept at minimum length in order to minimize the distortion they cause. This is sane enough thinking and also true to a great extent.
But although distortion caused in the signal path can probably be measured easily, it isn't destructive to the music signal per se.
You'd think that long cables inside audiocomponents would add noise and edgyness, or softness, depending on the cabling used. You'd also be forgiven to think that any powerampp that doesn't have its speakerterminals soldered straight to the circuit board, is a compromise. And it is very understandable to think that powercables should be as short as possible as well as cabling inside an extensionblock.
But these are all assumptions that I feel are only relatively true. I'll explain by taking some components and situations from practice as an example.
For instance, I had a McIntosh MA6900 integrated amp. Very expensive but you don't want to peak inside! Why? Because it is full of wires! The output transistors are in the middle of the amp. From there a bunch of wires go to the output transformers which, incidentally, are placed at the front of the amp. From there another bunch of wires go to the output terminals. In addition, there are a whole row of bog-standard potentiometers in the signal path such as volume, balance and tone controls. Although, the latter are officially placede outside of the signal path when in neutral position. Finally, there isn't a single audiophile components inside. The result of all this must surely be below par, right? Well I wouldn't blame you for thinking otherwise. I did too. I expected the amp to sound sluggish, soft and undynamic. The opposite turned out to be true. It sounds lively, dynamic, powerful and quite fast. It sounded quite a lot like my previous Bryston 7BST poweramps, only more musical. It also has extremely low distortion and noise figures. Even lower than my highly esteemed Jeff Rowland gear. How's that possible? I'd say clever design. In the end, it isn't the ingredients; it's what you do with them. All the wiring inside, as well as the output transformers and the presence of a tone control... in the end they don't add any noise or distortion. You can argue about the sound of the amp though. Fort its smooth yet dynamic presentation it either is or isn't your cup of tea. But don't call this amp coloured: tonally it is extremely neutral, again, reminiscent of the Bryston 7BST poweramps.
Second example. Speaker cables. Longer ones pickup more RF pollution and lend less grip over the speaker to the amp. I cannot argue with that statement. But is this bad in practice? For one, I haven't heard negative effects of RF pickup in speaker cables. But this is something that I haven't tested properly and shouldn't comment on. I have experimented with long versus very short LS cables though. The shorter ones do tend to sound more controlled. It seems as if either the amp has better control over the (bass unit of) the speaker or the cable adds less colour or softness over its length when it is shorter. But this is a mixed blessing. For if your system tends to sound overly analytical: this will get worse with short speaker cables. I wouldn't say that a long cable "distorts" the signal, but it does make the sound more fluid, less dry, more relaxed and, to me at least, more musical. There wasn't an event during my extensive experience with many, many components and speakers, that I ever preferred a shorter cable over a longer one. But this has to do a lot with taste. And my taste is toward the rich and smooth, less towards analytical. There is absolutely validity into saying that shorter cables can result in a more precise sound. It just isn't better per se. Also, I have heard short cables that sound soft while there were long cables that sounded tighter and more controlled. This depends upon the brand and type of cable too. But in general, shorter equals more precise/dry.
Powercables and extensionblock
Finally, the third example: the powercables and extensionblock. I'm sure that you can measure a degradation when comparing very long powercables to a direct connection with huge copper plates. But is shorter also more musical? I'm threading dangerous ground here as I know that there are many purists out there. Signals should be unpolluted. The whole truth and nothing but the truth. I can't fault that as it is true. But don't forget that you are listening to electronics; not real live people. If you make your signals as pure as you can by means of eliminating every inch of cable you can, you will likely end up with a sound that is overly controlled and perhaps too dry and sterile. Then again, I am aware that there are many people who like this kind of presentation. So, suffice to say that I am not about to pick sides here, merely pointing out that this is a somewhat relative matter. Moving on: shorter powercables do sound tighter and drier than longer ones of the same brand. I've tested this thoroughly and everytime the longer version would be slightly more fluid and relaxed compared to its short version. Extensionblocks are not much different. The sound of these depends greatly not only upon the quality of the sockets but also on the type of cabling used inside. Officially, the cabling should be as thick and as pure as possible. I've done many experiments with this and have also taken this to the extreme by eliminating the extensionblock altogether. You can read all about it here. A funny thing ws noted with a specific type of cable inside of a star-wired extensionblock: despite starwiring, all sockets still sounded different! The length of the cable differed, depending on the position of the socket, but the difference in length was about 5 cm! What's more surprising (in addition to this being audible in the first place) was that the socket with the longer cable had better treble in the sense that it sounded more airy and open, without sounding more brittle or edgy as you would expect. Quite to the contrary: the socket position with the shorter cable was more explicitly defined in the midrange but was also harder in the treble and darker. Needless to say: I used the exact same cabling inside, in the same direction etcetera; there were just no variables except the extra 5cm length.
To me, all the above makes clear that you just cannot simply say that shorter signal paths are by definition better. I do agree that they are purer or at least add less signature, but whether you perceive this as better or worse is entirely up for debate and very much a matter of taste. But I'll let you decide for yourself!