Upgraded version of the L-550 bestseller.
The L-550X is a 550 with a bigga Bando toroidal transformer, partly copper-plated chassis and the appearance of a DAD input label - rather strange since CD had been accepted more than a year before...
Circuit-wise no changes - see the L-550 page for detailed descriptions.
Like the MB300 tube monoblocks, the 550X was launched just after the Alpine sale so the early batches still see Luxman in hometown Osaka, later ones in non-descript "Japan" ; T-Tag is uniformly Alpine.
In Japan, the 550X cost 50,000¥ more than a regular 550 - maybe why it didn't sell too well. But since everybody already had an L-550...
Replaced by the L-560.
Nudies aplenty at the indispensable amp8.com and a real 550X here.