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.
routeman21
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: http://i.nextmedia.com.au/avhub/australian-hifi_reviews_2011-05_to_12_2011-07_yamaha_as-700_amplifie...
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: http://i.nextmedia.com.au/avhub/australian-hifi_reviews_2014_2014-02_yamaha_as500_amplifier_review_a...
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.