Well you need to look at each case in a little more detail, so here is my view, from listening and my engineering back ground.
Analogue cables, can and do have a varying effect (no link to price). As the type of material used, copper, silver etc... the construction, Oxygen free copper, plated in silver, type of insulation used and design.... and on and on.
With these cable you are forcing the signal you will listen to down the cable, same as you push the signal through resistors, capacitors and chips. So the design is in the analogue signal path.
In the digital example of a NAS drive, the hard drive reads from the the platter, into it's memory buffer, it's then sent in packet down the CAT5 cable, and checked when it is received by the Steaming player. If any packet is corrupt, it is resent. Next this packet data is loaded into another memory buffer. It is then fed into the DAC and analogue stages of the Digital Streamer.
The design of this process has been set up to protect it from external or cable issues, as it in effect "error corrects" it's self. The design advantage of a NAS playback system is the read errors and jitter timing issues in a CD playback system is removed.
Hence the NAS/Streamer system has potential to sound better than the CD/CDplayer. In my system this is true.
Digital cables, as long as it's well made, and not leaking any of the data, and causing high error correction to occur, then they should be equal.
I have experimented with a few SPDIF cables, but never convinced myself that I heard any real difference.
Main Cables, I am on the fence here, so dependant on the power supply in the equipment I think. For me with Linn Switch Mode Power supplies, I don't find much or any effect. Others do claim different. I use the OEM leads, plus a few RA mains blocks, because they give some spike protection and were easy way to convert UK plugs to a Euro mains lead for use here in Italy. (Plus the power supply here is flaky)
Tables:- For a NAS drive, unless you put the drive on a washing machine on spin cycle it should in theory not be effected, unless you get to many read errors, or mis sent packets. So a "sensible" surface should be ok.
For CD players, you don't want to much feed back or vibration, as you can again cause read errors and more Jitter problems. For me a good sensible table/surface will do.... again not related to price. Once again some players could be more sensitive than others, so it's not a predictable science in my view.
For Amps.... With my amps, never experience any change with the type of table I have used.... The claimed micro-phoning effect on electronics I can believe is technically possible, but does it in the real world get high enough to be heard.... Again equipment dependent.
Turntables.... Very critical, partly dependent on design of TT, you need to prevent external vibration and ground internal caused by the motor and rotating mass.
Hi Fi, simple hobby really hahaha
the statement was that some guy says is NAS drive sounds better when it was on some 950 quid audio table..... For sure he already had tried different CAT 5 cables. 
...... I can upgrade my audio and hear an improvement...... Changing my camera doesn't make me take better pictures..... oh and I was shooting some B&W film this week..
