Over the last 20 years my Yamaha R-8 has done an exceptional job powering a Heresy II Signature Series pair. More recently, having opportunities to acquire 2 R-9's, La Scalas and Klipshorns, I can say the R-9's do better than the R-8. I always loved the flat loudness feature on the R-8 and the R-9 has this as well. I strictly run with tone bypass engaged. Rolling the flat loudness allows for quick adjustments to listening conditions. I highly recommend both models.