Speakers That Won't Sound Too Smooth Or Soft with Luxman L-590AXII

I am curious to know the speakers that are matched to Luxman L-590AXII with success.

I have upgraded from the Luxman to Gryphon Diablo 300 several months ago but am keeping the Luxman as it has some special qualities that I appreciate. However, all speakers that I use with the Luxman seem to sound soft and unexciting. It’s just something that’s lacking or an incomplete sound, and I can’t find the words to describe it. It gets worse when smooth or warm sounding speakers such as Harbeth or Grahams are matched with the 590AXII. The more resolving and detailed Marten Duke 2s match rather well with the Luxman 590AXII, much better than Harbeth but still something is missing and doesn’t sound quite right. It was when I got the Gryphon Diablo 300 into the mix the Martens are showing more of their potential. 

So back to the question. Is there a speaker that actually sounds good with the Luxman 590AXII? Another 590AXII owner also found the amp to sound soft and polite when matched with Focal Sopra No.1. I appreciate the delicate and refined delivery of the 590AXII but not the soft and polite aspects of it. 

Any thoughts or experiences would be appreciated.