opa544 will not work as a Gainclone.

I used no input divider, and coupled direkt with only a 10k input resitor. I had no special distortion as proved by measurement. Of corse the chip has measureable crossover distortion. If you want to avoid this, use a class a amp. not a chip. There must be something wrong with your settup - or your expecations. Of corse there is not much more than distortion above 30W or so.
 
Anything anyone ever does with an opa544 will never work as an audio amp. It has almost no forward current bias in it's output stage. Horrible cross over dist. regardless of load. Great for non linear apps, but poo poo for audio. And that little hicup in the scope at the zero level is actually huge. If it's visible at all on a reg. scope then your ears heard it long ago.