Well I have no experience of the Luxman amp or the CDM1, but I do use the Pioneer A-50 and B&W Nautilus 805 speakers, albeit in different set ups.
I did try them together for a while and thought they worked well together. The A-50 is a very capable amp and produced a very clean, detailed & open sound with my 805's, but never fatiguing, perhaps slightly lean in the bass department but unless you're a bass freak you should be more than happy. The Pioneer certainly has enough power to drive most speakers with no problems, I would just worry in your situation about changing from a very old amp to a new one such as the A-50, could be quite a culture shock and may take some getting used to.
I wonder if maybe slightly warmer sounding amps such as the likes of Arcam or NAD may be a better bet for you, but then, as I say, I have no idea about the Luxman so I may be wrong on that front. The Pioneer should be widely available so maybe some kind dealer somewhere might let you demo one at home or failing that you may be able to take your speakers along to the dealer?