Sonus Faber Guarneri Homage and Single Ended Triod

I used Cary 300B Signature to drive B&W N805 without problem, but it took a year to break-in the N805. I also tried Forte 4A(50W class A) to drive N805 and found it was only a few more powerful than Cary 300B Signature. Then I bought B&W S805 and found they are much easier to drive than N805 thanks to their bigger magnet in the woofers. At that time, it took only 8 hours to break in the S805. I also tried Welbourne DRD 300B & J.C. Verdier 300B to drive S805 without any problems. I found J.C. Verdier 300B is the most powerful one of these 3 300B amps. So I sold the Cary's & Welbourne's.

B&W N805 & S805 both are 86dB of efficiency, but one is obviously easier to drive. So, efficiency doesn't make a lot of sense in my case maybe because I listen to them in nearfield- 7 feet to left & right speakers.
Actually, I had also tried Fi 300B for several days without success. I think running out of power on bass transient or not depends largely on how much energy stored in the output transformer of SET.