speakers with balls

Uh.... Not even close. Those things don't use line level inputs. Those are low gain, digitally manipulated, speaker level amps, and the measurements make that very clear. Those speakers present a fairly benign load to the amp in the bass region, but they in no way excuse the amp from driving a load just as it would a driver directly. 

Cerwin Vega XLS-215  .----

Pi Speakers. If you can build, all their models come as kits. Assembled they're reasonably priced. Better than Klipsh.

Tannoy Legacy Arden; they'll rock, sing, swing, trumpetize, energize, dynamize, precise image, huge soundstage at same time, lively, extremely musical speakers, doing it all well distortion free very loud or of course also very softly, and they like lots of power contrary to what many believe about Tannoy's liking of small tube amps. You'll just need over 200hrs run-in (at some high volumes too) before they reveal their full and true nature. They are just very engaging full range speakers with a natural and lively sound, without fatigue.

Interesting thread . I own Zu Omens, JBL 4312a’s that are pristine on Sound Anchor stands and Klipsch Heresy III’s . I love my Zu’s . I had a Modwright KWI 200 paired with the JBL’s and it was too dry . The JBL’s come to life with tubes at about 100 Watts . The JBL’s are near field studio monitors . And while sounding substantially better than the Heresys, are meant to have a flat response for mixing . The amp matching is important to get that sound you want . For me it’s KT88 or KT120 in a push pull configuration. I run the Zu’s on low power tubes . If I went SS, I’d get a First Watt. Also the best description of  Zu is “ YOU EITHER LOVE THEM , OR HATE THEM”. For me it’s Love them . But I tube roll when I change music genres, YMMV . Happy Listening , Mike B.