Well, it has been over five months since my last contribution to this particular thread. I have some new information that I feel compelled to share.
I purchased the Luxman507u, and have been comparing it to my former unit, the 505u. Here are my impressions:
- The 507u is superior in terms of clarity, depth of stage, and overall dynamics.
- The 507u is superior in terms of power.
- The sound 507u appears richer and more ambient.
In a nutshell, I can tell you that while its cost is double that of its predecessor, its sound quality is indeed noticeably superior.
I purchased the unit from a Japanese-superstore with a bank transfer. Some people have taken the liberty of questioning the ethics behind my purchasing from an overseas store. While I can understand the desire of others to purchase only from a US-Luxman dealer, I politely contend that these units, which are masterpieces of the industry, should be made available to the masses - but the current middle-man cost additions, which are undeniably exorbinant, unnecessarily prohibit this from happening. I would also add that the warranties of all US-Luxman units are limited solely to their original purchaser, and are utterly non-transferable upon resale.
As an electronic technician with 30 years of experience, I can assure based on experience that using a Japanese transformer (chiefly Sanyo TSDN15LU, and Nissyo NDF1500U) will not degrade sound quality. Claims to the contrary are incorrect - years of both personal and consumer products testing have yielded no evidence to support such a claim. Japan, Brazil, Taiwan, parts of Columbia, and North America use 100 to 117 volts, 60HZ. There are no issues using these transformers in the aforementioned countries. But I would not recommended using European 230-volt, 50HZ against the USA 117-volt, 60HZ via transformer. Additionally, the transformers I recommend will stay cool despite hours and hours of continuous operation, and provide unwavering 100-voltage output - which eliminates the need for a power conditioner.