Fahnsen:
That's not my experience.
You'll always hear the difference between two speakers. Only if the speakers are demanding (or, as some famous audio engineer put it: Badly constructed), you'll hear much difference between two amps. Unless those amps distort the sound, that is, But then many amps do of course.
As for sources, it depends.
There's a recent test showing that 'audiophiles', not knowing what they actually hear, are unable to distinguish between an original CD track and a copy that's recorded from a cheap CDP, through 5 metres of cheap, thin wire, to a cheap PC soundcard...
I think this ability to not tell the difference is an interesting point, but it still must remain that the source is the most important, this doesn't , though, mean that the most funds should be spent here.
I don't feel that is a contradiction either, due to the law of diminishing returns and you may prefer a speaker 'sound' that just happens to require very powerful (expensive) amplification to control 'drive' them.
I feel the main sound modifier are the speakers, as they can be so tonally different but the system must have a synergy between components. This is where some technical information on speaker repose and load is useful to help such decisions ( people must no shy away from tech specs as if its just for the boffins, although Japanese amp power specs are not that helpful here!)
For a blind test of 3 CD players , I took the then wife and we could both tell the same one being replayed each time and also disliked the same one.
Reviews must always be taken with a pinch a salt, as everyone has a preferred sound bias (warm full, detailed fast) and each mag. seems to prefer particular sound (like different Churches with the same God) and each item is system dependant, so will it work so well in yours?
Also some magazines review so many items a month they can hardly be detailed.
One also has to remember the technical ability of some reviewers and their inability to understand technical issues and can in some circumstances offer advice which later is proven incorrect.
Some magazines also seems to put some things into print. ( with all the best intentions ) and can't then back down from that position and have to maintain the face by reiterating a falsehood.
So the hi-fi world is a self promoting enterprise which has to be used as entertainment with your own ears and more importantly your wallet deciding.
Do you really trust Simon Cowell?