Luxman 505UX vs. Luxman 550AX Integrated Amps

Has anyone compared both of these integrateds? I own the 505UX and like it a lot but am looking for more solid state slam & punch. I actually borrowed the 550AX Class A amp for 1 month about a year before I purchased the 505UX. The only thing I remember about the 550AX was that it sounded much more powerful than it's power rating suggested due to it's high current.
I realize the Luxman's are very refined and have finesse but my 505UX does rock out so basically what I'd like to know is if the Luxman 550AX is more ballsy than the 505UX.
I had a 505U and I got a pair of Proac D40R' seemed quite clear to me these speakers needed a bit more power and quality.

I ended up with an ex-dem Rega Osiris-it did both jobs-more more slam but with quality and detail-this might not be the amp for you but with a decent trade in on your Luxman you will be able to pick up a suitable replacement amp albeit second hand.
Any 550 class A will beat the others.

Awhile back I researched the integrated amp field looking to simplify but not sacrifice, my system. My speakers are Salk Sound SS8's that are rated at 87db and pretty much a flat 4 ohm load.

After listening to intergateds from Luxman, Accuphase, Musical Fidelity, etc. I decided on and purchased the Jeff Rowland Continuum S2. It is the most dynamic amplifier I have ever heard. It has the layers of sound, extension and finesse of a really good tube amplifier (VAC) while possessing the drive and dynamics of top notch SS gear (PASS Labs).

The JRDG Continuum S2 is also available with a DAC (which I've heard is pretty good sounding) or a phonostage which mine has and it is pretty damn good, though my Herron VTPH-2 smokes it!

Good luck in your search.

You can't go wrong with Luxman. On paper, the 550AX is the better amp. But it's really up to you to decide whether it sounds better. Is there any chance you can audition the 550?
I did audition the 550AX about a year before purchasing the 505UX. As stated in my opening post, I only lived with it for about a month or less and the only thing I remember was how much power it had for 20W. I wish I could have spent more time with it. I've owned the 505UX for a year and have put it thru the paces so I know it's tendencies.

Thank you for mentioning the Jeff Rowland. I've never heard one but will look into it.
Second recommendation for the Rega. I own their Isis CDP and it their top of the line stuff will compete with anything out there.
Well I've had my L550ax for about 2.5 years. I too wanted to simplify, I had a CJ Premier 140 Tube amp and and EAR 868 Tube Pre. Can't say the Luxman is better but I can say I haven't missed the tube stuff. Lux is easier to live with, does a great job with my Sonus Faber Electa Amator II's and the MC pre works well too. Sonus in my main system but my other system is Magnepan 1.7 based and the Lux works fine with them as well. Can't turn the thing past 12 o'clock in either room. For reference my other integrated is a NAD C375Bee. Damn nice as well. I've been an audiophile kinda guy for a long time but (almost) off the gear bandwagon (sort of). Except for the new Chord Qute EX DAC with the Lux. Of course. Well that's another thread. If you're in the NYC are glad to demo over a weekend.

Ok, cool, and sorry about that.
Very good info. Thanks!
My first audition was the Luxman 550ax and I thought it was terrific. The next step, of course, was to listen to the Luxman 590ax. It was a huge improvement over the 550ax and was more expensive. After listening to both units several times, I decided to replace my Ayre AX-7e integrated amplifier with the Luxman L-590ax class A amplifier. In addition, I wanted a fully balanced integrated amplifier like the 590ax.

I was "surprised and shocked" at how much better the Luxman was over the Ayre. Of course, there is a huge price different but I felt the extra dollars were justified because of the improved sound.

In summary, the music is fuller, with more detail and with better bass control. I am hearing more things than I did with the Ayre AX-7e amplifier. The mid range is outstanding. I do not understand but classical music sounds better on the Luxman than the Ayre. The music is clearer, more airy and easier to listen to. Overall, the new amplifier sounds excellent in my system. I listen to classical, jazz, blues, country and new age.

I recommend you give the Luxman 590ax a listen. It drives my Sonus Faber speakers perfectly and class A sound is excellent.
Comparison to the similarly-priced Ayre AX-5 would have been interesting.
I prefer Ayre digital and Luxman class A.
I had a Rega Osiris and replaced it with a CJ Premier 140 with Teflon upgrades.  The CJ was a much more powerful amp.  It had a lot more dynamic energy and harmonic richness.  I have since moved on from the CJ>.  However, I found the Rega had a sweet spot.  To low a volume and it was bland.  To loud and it definitely told you to turn it down.  Harsh and fatiguing.  A Isotec Syncro made a huge improvement to the Rega.  At the right volume it was very nice.   I guess I am saying, I was considering a Luxman M600a, but if it performs like a Rega, its not for me.
In about 6-7 weeks Luxman will release the Luxman 509x integrated for $9500. It is a AB design and going to be their flagship integrated. If I get a passive speaker for my office I am seriously looking at this integrated to drive the speakers.
How about a Yamaha AS 701 or AS 801 as an alternative? See here for a test of the previous AS 700, essentially the same amplifier but lacking the digital inputs:
The test of the slightly less powerful AS 500 shows that also under simulated real loads frequency response is as flat as it gets (within +/- 0.05 dB), and better than almost all other amplifiers on the market, even very expensive ones. The implication is that this amplifier has no sonic signature at all - a straight wire with gain:
I owned a Luxman L-590AX integrated for about a year.   It’s a great amp and provides excellent value for all the features it has.  I’ve gone up the food chain a bit to Accuphase E-600 (twice the price as the Luxman when you add the cost of a photo card).  The current Ayre AX-5 Twenty is better than both IMO but the Luxman is far better value.