Having just got a NAD D 7050 (2 x 50 W @ 4 ohms), and still having my Rotel RA-05 (2 x 40 w @ 8 ohms), I can honestly say that the NAD can only drive my Focal.JMlab Chorus 714s (8 ohm impedance) at about half of the volume that the Rotel manages. I suspect bass response is negatively affected too.