Consider a sportscar analogy. Every so often a driver might enjoy taking it out for a spirited drive on a winding road like Sunset Way, Muir Beach, CA. Such a driver might buy better tires that perform better but will not last as long. The car does not need those tires and the driver does not need do this type for driving. It is also dangerous, but...
I was able to illuminate the ATI3005 clip indicators driving the Salons below reference volume (on the AV8801) with Sara McLachlan's Surfacing album, coinciding with the piano strikes.
Unfortunately, most amps, including my Parasound A51, do not have clip indicators. I am quite certain the A21 is clipping peaks below -10 on some content since the ATI3005 has. The A51 is spec'ed at 1.5 DB headroom so it can likely produce 600 watts into 4 ohms and the ATI3005 is more powerful.
Listening to my friend's A21/F206 system, I do not believe speakers reach the limit of their performance before the A21.
Clipping is not always harsh sounding, sometimes it limits the performance of a speaker before distortion becomes objectionable. A listener not know this is occurring. A reviewer would know who has heard their speakers with other amps.
The difficulty lies for a enthusiast to determine if they are limited by an AVR and should consider a 200 to 300 watt high current amp with power reserves required to drive difficult loads.
- Rich