Luxman 590AX II Break-In

From a number of comments it is starting to sound like a speaker / amp mismatch.

The only other input I can add is I spent a couple hours with a Luxman M10-x and a set of Magico (A3 I think) and I have to say, it struck me like the OP’s comments on his amp. There was no warmth or naturalness to the sound.  

It’s quite possible that the speaker / room/ listening position is manifesting a bass null; I’ve battled this exact symptom for years. If your listening position is near the center of the room this is most likely the culprit.

Perhaps SS Luxman Class A is not their thing.  I've only run Sugden Class A and it was a bit bass shy, but not what you describe, the midrange was in order.  As mentioned before, my Luxman 509X is a beast, but then 120wpc Class A/B.

It drives ATC SCM20PSL monitors which regularly torture amps.  They play well together.  Hope you figure this out to complete satisfaction.

@jeffreyw I was reading a post of yours when I was researching the Luxman M10X amp. I am looking for an amp for the KEF Blade 2 Meta and was thinking of the Rotel Michi M8 mono. It was suggested to me to check out the M10X over the Michi by a former Michi owner. I know the Luxman m900u and did not think it had enough to properly drive the Blades. Though the new M10X is supposed to address that.

The post of yours that piqued my interest was your comment about your dealer preferring the Rotel Michi to the Luxman gear and that that dealer sold both lines. Have you heard the Michi line?

When I auditioned the Luxman gear for a potential KEF Reference 1, I was considering the 509x integrated but the m900u was so much better.

The other amps I am considering for the KEF Blade are the CODA #16, KRELL KSA i400, Luxman M10X, and the Rotel Michi M8 monos.

The KRELL XD lineup is maybe something for you to checkout if the Luxman does not work out. The KRELL Dou 175XD (sold) was great with my KEF LS50, though I suggest the KRELL Duo 300XD for the Reference 1 Meta.

Krell DUO 300 XD For Sale | Audiogon

I don’t think it is your amp. As a comparison, I run a 509x into Dynaudio Contour 60i, and the bass slam will exfoliate your face and cause your bones to vibrate. I’ve heard the littler Luxman class A do similar things with Contour 30i. Your speakers are the problem or, rather, the synergy between speaker and amp is your problem. My bass profile was immediate; and after 200 hours of listening, the sound merely congealed more with treble and midrange. I’m sorry you are having issues and am sure it is frustrating x10. Swap out speakers and see what happens. The 590 is a stump puller and is not your issue. Steller amp.