Thanks to everyone for the precious advice. And I have to confirm that you were perfectly right.
Yesterday afternoon I decided to make a little tour de force: I loaded my Brio amp and Nad 525bee cdp in my car and went with my cds to first shop. I auditioned Rs5 speakers with my amp and cdp: they sounded ok but overall a bit lifeless and flat. I asked to switch my player with Rega Apollo and.....wow, it made all the difference, like day and night: music became alive, present in an holografic way, but with a sweet delicacy, not harshness at all. I asked to switch speakers with a similar model from Castle they had on display: the result was undewhelming under all aspects.
So I borrowed Apollo cdp and headed to the second shop. I auditioned MA RX6 with my Brio amp and Nad cdp: good low frequences but again a bit dull and not soundstage at all. I switched to Apollo player, things became better but still not right, better detail and musicality, but still lack of soundstage and sound overall a bit fatiguing. I asked to try with a more powerful amp, Nad c375bee.....the RX6 came suddenly truly alive, the music was finally there as I wanted, and the difference switching players now was very thin. Sill, and now it's probably a matter of personal taste, a bit too much bass and high frequencies a bit rolled off. I asked to try a pair of older Monitor Audio RS6, and for me and my kind of music seemed the right answer: less bass (better, let's say less precise bass) but midrange and highs like I wish them, good scene and soundstage, and that also with my kit (but leaving undisputed supremacy to Apollo even compared to Nad 545 cdp (again my personal opinion only)). Just the presentation of the RS6 was a bit too much "in your face" and gave a slight hint of fatigue.
So the final decision was made: I went back to first shop and bought both Apollo and RS5 speakers........and I'm truly happy (most important and unbelievable......my wife supported me in buying also new player
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Praise to you and also to WHF team for January issue's supertest!