I had a 505U and I got a pair of Proac D40R's....it seemed quite clear to me these speakers needed a bit more power and quality.
I ended up with an ex-dem Rega Osiris-it did both jobs-more more slam but with quality and detail-this might not be the amp for you but with a decent trade in on your Luxman you will be able to pick up a suitable replacement amp albeit second hand.
I ended up with an ex-dem Rega Osiris-it did both jobs-more more slam but with quality and detail-this might not be the amp for you but with a decent trade in on your Luxman you will be able to pick up a suitable replacement amp albeit second hand.