Brid-Series: The build quality of the D Series is better. The front plate of these players is made of metal (except D-111, it's the cheapest model). The best player is the D-109. It is part of the 109-line (LV-109, D-109, LE-109), which is even better (in quality) than the 117s (KD-117, D-117, LV-117, LE-117, T-117) the best of the brid-series. The tube CD Players are also quite good (D-103u, D-105u, D-107u).
The DZ Series has some good players with many functions (DZ-112, DZ-122) and some cheaper models (DZ-92 (cheapest), DZ-111, DZ-121, DZ-120). And there's the DZ-03, which is the silver-golden version of the D-103u.
The most players are built of Sony parts. But there are also some players with Toshiba inside (D-103/D-404, D-105/D-405, DX-103, DX-104).
And no, the higher numbers aren't the better players! You have to know the year in which a player was built and in which series.
I can't really explain it, so here's a list with all players sorted by the year of build. The first is the cheapest, the last the best.
< 1986 >
D-90
D-100
D-102
< 1984 > (built with toshiba parts)
D-103 / D-404
D-105 / D-405
< 1987-1989 > (built with Sony parts)
D-111
D-113D (it's a D-112 without D/A Converter; it's a CD transport)
D-112
D-113
D-115 / D-01
D-117
D-109 (the best Luxman player)
< 1989-1990 > (built with Sony parts)
D-103u / DZ-03
D-105u
D-107u (later version of the D-105u without Digital Outputs)
< 1989-1992 > (built with Sony parts, except for the 92)
DZ-92
DZ-120
DZ-111
DZ-121 (almost identical with the 111, but with an optical digital out, instead of a coaxial digital out)
DZ-112
DZ-121 (almost identical to the DZ-112, but opt. digital out)
< the first players, 1983 >
DX-103 (Toshiba XR-Z70 clone)
DX-104 (Toshiba XR-Z90 clone)
300-series: The players of the 300-Series are built of Sony parts and the pick ups from this players are still available. The player with the highest number the best.
If there's something wrong, please tell me, whats wrong, so I can correct it.
If you want to have some other informations, let me know...
Regards