I sold my Wavac 300b tube amp and Pass XA25 because they were collecting dust as my class d was superior to both to MY ears.
You used an SE 300b or a XA25 to drive a pair of Wilson WP 5.1’s!!!!
No wonder you think the Class-D AGD is the be all and end all to those 2 amps, which btw had no hope of driving the 5.1’s correctly, look at the combined impedance and -phase angle, the EPDR is around 1 to 1.5ohm in the bass very hard to drive. And like I say now also even for the AGD, but it’s better than what you had.
https://www.stereophile.com/images/archivesart/watpup5fig03.jpgIf you wish to learn a little about EPDR load of speakers on amps go here.
A demanding load, its impedance (fig.2) reaching a current-hungry 2.4 ohms in the upper bass, although this will be moderated by the relatively innocuous phase angle in the same region. The rise in impedance above 100Hz is due to the low-pass crossover; the low port tuning is revealed by the magnitude saddle between 20Hz and 40Hz.
https://forum.audiogon.com/discussions/epdr-more-important-than-impedance-alone