Can someone point me in the right direction? LP player / Preamp / Dragonfly Red...

They are 6 ohm, but really act more like a 4 ohm speaker with such a demanding load. The Onkyo specs only show a rating for 8 ohms. This usually means the amp doesn't have the power/current required to drive power hungry speakers like the Kappas. The 8.1 specs state a minimum of 50 watts.

What is the size of your room? And how did the Kappa's respond to your Sony?

I read that the Onkyo was stable down to 4 ohm.  And I thought I read the wattage would be closer to 66 WPC @ 4 ohm from that amp (I'm no Ohm wizard though)

Room size is 11x20 (with speakers on the short wall about 6" from each corner slightly angled in).  They respond pretty well to the Sony, which is supposedly 100WPC @ 8ohm.  

I've read everything from give them 300W to a 44WPC will make them thump.  Its very confusing...

I found this insightful - but I'm still confused haha:

https://www.reddit.com/r/audiophile/comments/7fcc5r/can_someone_explain_why_a9010_drives_harder_at_4/

You're right, specs vary online.
This one has a rating of 70w into 4 ohms.
https://www.cnet.com/news/low-costhigh-performance-contender-onkyo-a-9010-integrated-amplifier/

I think the real issue is that the Kappa's are more demanding than a 4 ohm speaker. I dont see an impedance curve which would show how often there is a demand for high power/current.
  The Onkyo will certainly drive your speakers, but you may be missing out on detail and texture in the bass frequencies. It's possible that the speaker's demand during peaks and transients may push the amp into clipping, which is distortion.

With this combo you are at the very minimum of what the speakers demand. Have you looked at the next model up the ladder?, I forget the model number.

I think the real issue is that the Kappa's are more demanding than a 4 ohm speaker. I dont see an impedance curve which would show how often there is a demand for high power/current.
  The Onkyo will certainly drive your speakers, but you may be missing out on detail and texture in the bass frequencies. It's possible that the speaker's demand during peaks and transients may push the amp into clipping, which is distortion.

With this combo you are at the very minimum of what the speakers demand. Have you looked at the next model up the ladder?, I forget the model number.

I certainly don't want to spend 400 and run into problems with clipping!  There is THIS I found last night and its 299...  https://www.ebay.com/itm/Onkyo-A-9050-Integrated-Stereo-Amplifier-Black-2x75W-Channel-MPN-A-9050/223...

Would this be a safer bet?  I appreciate your help, thank you!