From my experience the 509X is as neutral as it gets. Very smooth and crisp, never fatiguing. Only thing I thought it somewhat lacked in my setup was the mid-bass and bass. I demoed a Vitus RI-101 side by side and with the Vitus it felt like I added a sub in the room (nothing else was changed other than swapping amps). This was with the Martin Logan speakers I had at the time. Same thing with the Gryphon Diablo. Both are double the price, so the Luxman is a great value for the money.
Eziggy, good comparison between the Luxman L-509X and Vitus RI-101 and Gryphon, presumably the Diablo 300. Although I do not have experience with these units, a friend who is in the hifi industry had listened to the L-509X and Diablo 300 and related the same experience. The Gryphon is said to possess the raw, powerful and dynamic sound whilst the Luxman is more neutral and delicate in its presentation with more focus in the midrange.
Perhaps your Martin Logan speakers require more from the amp to open up, or the Vitus and Gryphon are better matches to the ML. With less demanding speakers particularly delicate and detailed sounding designs, the Luxman work very well. Yes, the Luxman is value for money, that I would agree.
