Just a quick update:
At the last moment, I decided to have a check with both Arcam s20 and Elex-r rather than going directly towards SA30. It turned out to be a wise decision. I have both of them at home and found elex-r a good match - driving the R3 in a "everything-seems-to-be-correct" way. The muffle in male vocal is totally gone. I will keep the elex-R, while still missing the sound from the YAMAHA rn-803D, which give a hall sound to the music. This also makes music sounds more real and with a bit better layered structure. The fatal issue is that 803 cannot handle the resonance of R3 as well as the elex-R.
If I'm right, it is something related to - at resonance frequency- low impedance - high current demanded suddenly - large electric force vs. resonance - put the cone back to its place ?
Does that mean, the RN803 should be combined with some "easy-to-drive" speakers, such as Focal aria 906 (8ohm with 4.6 minimum, 89.5dB/2.83V/m). While R3 needs much more control since it is 8 ohm with 3.1ohm minimum, even down to1.5ohm at 39Hz, with another dip to 2.2ohm at 226Hz. -referencing hifinews).
If I want to keep the RN803D for another setup, what would be the best speakers to feed her?