hypersound just found this comparison on audiokarma.
At this level, I do not think you can say definitively one is better than the other. Both are incredible sounding and have their respective strengths and weaknesses. It is more about a different flavor of presentation, if you will, that one brand takes as oppose to the other. When I auditioned the Mac amps I was floored at the depth of the soundstage - they all had it. The MA6600 in particular had a very nice weight behind the music, possessed a very nice "liquid" sounding midrange for vocals and had a nicely detailed yet smooth high-end with no perceptible fatigue. The Mac's are very musical - if you like hearing chairs move or pages being flipped in the orchestra, this is NOT the amp for you. If you like music…and being emotionally stirred by it, then you can do no better than one of the McIntosh amps.
The Lux possess the same musicality and adds a bit more dynamic swing to the music. In case you haven't guessed, I like "musical" amps; I cannot stand the sterile "analytical" amps of which there are many examples. The 507 is NOT an analytical amp - it's presentation is slightly warm and sweet but neutral. You will miss none of the detail but it is not in your face nor does it leave you hanging by a thread - it lets you hear everything intended in the recording. The 507 has the most fantastic bass I have ever heard in an integrated: it is textured, deep and does not posses a one note quality.
I am very susceptible to harshness in the highs which is why I only use a soft dome tweet in my speakers and I have sold many an amp simply because of too much detail and grit in the high notes. The Lux excels in the highs and lets you hear all of the detail one could ever want but it is smooth with absolutely no harshness or grittiness. The Mac amps possess this same ability in the highs.
In terms of soundstage, the 507 does not have the depth of the Mac amps but it is wider and extends well beyond your speakers. Every time I listen to the 507, absolutely zero sound comes from the speakers - it extends horizontally, in proper placement, and it is eerily realistic, especially with live recordings.
Both amps have tremendous flexibility and connectivity: tone controls (which was a must for me), phono stage and headphone amp. I could find no other example of a modern amp that had the type of functionality of the Luxman or McIntosh (well, except for Accuphase, but I am not a millionaire).
To me it is all about presentation. I do not feel the 507 was any better than a McIntosh integrated of the same specification/price. Just different. In fact, I am upgrading my second system and it WILL be driven by a McIntosh.
