Anyone tried Devore o/93 with Sugden a21

You might ask David Cope at Old Forge Audio in Connecticut. I believe he carries both Sugden and Devore.

As I type I am listening to my O/93's with an ARC Ref 150SE (160 beautiful tube watts) and they sound mesmerizing. It is emphatically false that you need to worry about having too much power for a given loudspeaker so long as gain is correct. That said, my 8 watt/channel Ampandsound Nautilus sounds gorgeous with the O/93's too. 

"Shouty" and "hard in the high frequencies" can only be due to system synergy. The "shouty" part could be due to sub-par room placement but the "hard in the high frequencies" could be any number of things. The O/93's SEAS soft dome tweeters are anything but inherently hard. I am not familiar with your amp. I auditioned the O/93s at Don Better's home-based store with a Sugden preamp and a VAC 150 watt power amp. 

All I can tell you right now based upon the very limited information you have provided is that you need to find a way to borrow someone else's amp, solid state or tube, and decide for yourself. The O/93's LOVE Auditorium 23 speaker cables.