Going linear - The Luxman 507ux

I would like to seek advices on the Luxman amp. I am interested with the 507xuIi and the 509x. I would not be able to audition them as there is no luxman distributor in my country. I would be ordering and shipping them from oversea. With a price premium of about 40% over 507xuIi.  Sonically what are the edge that 509x has over 507xuII? Is there a huge jump in terms of sound quality?

thank you

I noticed that there is big disparity in the prices of Luxman across the world. In US the retail price are similar to Japan. In Europe the 507uxII retails for about USD 7.5k and some of the Asia countries are priced similarly to Eroupe.

@erik_squires ,@jetter, Thank you for the advice.
I am from singapore where the electricity is 230 V 50 Hz. I originally plan to buy from the Japan 2nd hand hifi dealers where a 507uxII is about USD 3.6k a new one is about USD 4.8k. But this would require a step down transformer.
I contacted the luxman distributor in hong kong and they agreed to ship a new luxman 507uxII to me at USD 5k inclusive of shipping charges. The hong kong model is 220 V 50 hz similar to my country. The 509x would cost USD 7.5k.

@steveashe Glad to hear that you are enjoying your l507uxII so much. This has given me much needed reassurance on the amp, especially since I do not have the chance to audition it.