keeping perspective on evaluating improvements

OK, so I know we're all guilty--reviewers perhaps even more so--of engaging in hyperbole when we describe differences, and particularly improvements, associated with new/different components.

But what about keeping things in perspective?

Over the last couple of months, several items that might be described as power conditioners have passed through my listening room.  Most of them made no difference at all, or at least none that I could perceive with my two left ears.  The PS Audio P5, however, certainly does something.

(1) the bad.  The sinewave setting actually introduces a low-level low-pitched whine (120Hz??) through the speakers (with no music) that isn't there otherwise.  Multiwave reduces it, setting 6 (the highest) eliminating it.

(2) the neutral. It does not reduce the low-level hum (60Hz) from the integrated's transformers.  (That story is for a different thread.)

(3) the good. With it in the system and playing music, the music sounds somewhat more present, alive, vivid, full-bodied, perhaps slightly louder, the soundstage seems a little deeper, solo instruments a little more spotlighted.

But it's not, I repeat not, night and day.

Is this worth 3.5K to me?  No.  Might using that 3.5K together with what the current integrated cost in order to purchase a better amp achieve a greater overall improvement in presentation (and less hum)?  Very probably.

Am I keeping the P5?  No, it's going back, because the improvement is not that great, and some of it can be achieved very cheaply (by fractionally goosing up the volume control on the amp).  And also because, with a significantly different iteration of the P5 coming in April, it's already obsolete (and therefore losing value even before I drive it off the dealer's lot).