@ryder - I’m using the Luxman 590axii in my office system. Listening as I write, taking a short break from work. I’m using Buchardt s400 mkii speakers. The sound is warm and I know exactly what you mean. 

However, for my office, it actually works to not be overly distracting. A local dealer is coming over to allow me to demo the SoulNote D2 Dac, which apparently has a more forward presentation. I’ll report back on how that goes. 

It's definitely not a power issue.  If it wassn't for the FTC regulations on pre-heating an amplifier before testing that's a 120W amp.  Their desire to keep the same form factor as the 509 is the only reason it's rated so small, and so long as you don't attempt to run it at 30W for an hour it is superb. 

Um, Given your choice of speakers and what you are looking for I do wonder if that is the right amp for you.  How about Klipsch Heresys? 

Have been using for the last couple of years with Klipsch Forte IV; not everyone's cup of tea, I know, but neither are overly bright speakers with dome tweeters.

Be aware that the Luxman L-590AxII is not merely a 30 WPC amplifier.  The 30 WPC refers to where the amplifier remains in class A bias into 8 ohms. Beyond that point the amplifier moves into class A/B with considerable power. In a review in UK’s HiFi News Ken Kessler drove his Wilson Alexias to “decent levels” and “sounded like it was made for KEF LS50s - the latter famously hungry at 85 dB/1W. Paul Miller measured 2x95 watts into 8 ohms and 2x165 watts into 4 ohms with enough current available to produce 303 watts into 2 ohms and 170 watts into 1 ohm before electronic protection activating.  Maximum current capability is 13 amperes. Noel Keywood basically seconded those measurements when he (and John Myles) reviewed the L-590AxII in the greatly missed HiFi World.  So unless you have a palatial listening room, I imagine the 590 should joyously drive any reasonable speaker available today.       
I have owned and loved my L-590AxII for 7 years now and have had the opportunity to hear several speakers at length with it.  These included the Martin-Logan CLS2z and ReQuest (before I moved), Monitor Audio Gold 100, Bowers and Wilkins 805 D4, Magico A1 and Sonus Faber Electa Amator III.  In all cases the amplifier proved itself dead nuts neutral allowing the speaker to show its true color(action)s.  The CLS’s sounded exactly like they did on my (now departed) Krell KSA150 - astoundingly revealing.  The MA Golds were metallic and rather harsh, the 805’s a little bright but with bell-like top to bottom clarity, the Magico’s were rather boring, and the Electa’s rich and seductive.  For the last year the 590 and I fell in love with the Sonus Faber Maxima Amator, a big step forward in overall capabilities - especially neutrality - from the Electa’s, without losing the Electa’s suavity.  So my experience seems to indicate that the 590 will play nice with most any speaker that works with your taste and your room.

JBL 4367 or 4349 would be a nice match.  Also something like a Borresen X series if you are not critical about imaging.  Lastly TAD monitors will work well.  

 Probably a power issue you’re trying to run some fairly inefficient and hard to drive speakers on 30wpc. I’d look for something well into the 90db+, 8ohm. Better yet something that reaches 94db @8ohm.

Correction.  My Acrolink pc’s are: 7N-4030 II.   This review describes the sound as: ’darkish warm - yet balanced’.   If Acrolink has a house sound, this might explain what’s happening.    Perhaps, experiment with different cabling,   Good luck!

Sounds like a power issue. 

Maybe a more upfront speaker like Volti.  

Just a swag but my gut says the ATC suggestion is a good one. 

I had the L-550AXII and own the 595ASE. The 590 and 595 are more alike than different. The Class A Lux integrated's sound best with higher efficiency speakers with easy to drive impedance loads. In general, if the speakers sound great with tube amps (30 watts or so) they should also sound great with the 590. 

@celtic66 

Of course you’ve provided no info for what is upstream

The OP’s upstream components are listed in his Virtual System.    Simply click on his Username.  

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OP:   Nice system!   I have a couple of lower-end Acrolink 7030 power cables.  In my system, they were on the warm side.  Full-bodied, leaning toward too much so.  After replacing them, the SQ became more vibrant.  I have no experience with the upper-tier Acrolink models.   YMMV

I will help you if you are close to Los Angeles, CA.  My system sounds below. Alex/ Wavetouch audio

You Don’t Know You’re Born - Mark Knopfler,  -- My system

Not the Luxman 590AXll, but rather the Luxman 509X running ATC 20 passive monitors on custom stands provides great impact, high resolution with very good sound stage.  Very non-fatiguing, but live.  Just my 2 cents.

Of course you've provided no info for what is upstream, so you may be looking for love in all the wrong places.  Cheers

The Luxman apparently has an inherent sound characteristic that doesn’t jibe with your personal tastes, and given the speakers you’ve tried it may not be overcome with different speakers.  What is it specifically that the Luxman does better than the Gryphon?