Certain Japanese players, which are considered to be of higher quality or of greater capacity for quality playback than the North American units, are occasionally imported by enthusiasts. These include the LD-S9, HLD-X9 and HLD-X0. All three are manufactured by Pioneer and all three contain technology that was never officially available in North American Laserdisc players. The LD-S9 and HLD-X9 share a highly advanced comb filter, alowing them to offer a considerable advantage in picture quality over most other LD players when the s-video connection is used. The comb filter present in these players is unique and is purportedly the finest comb filter ever used in consumer A/V gear, it is still currently in use in Mitsubishi's top-spec CRT rear projection television sets (the Diamond and now defunct Platinum series sets) and Pioneer's Elite line of rear projection televisions. In addition to the advanced comb filter, the HLD-X9 contains a red laser pickup which significantly reduces crosstalk and picture-noise levels compared to players with the traditional inafred laser, it can also read through all but the worst cases of laser rot and surface wear. The HLD-X9 is, lastly, also a "MUSE" player, capable when properly equipped of playing back high definition laserdiscs, called Hi-Vision or MUSE discs in Japan. The HLD-X0 is Pioneer's original MUSE player, and is the player of choice for many enthusiasts despite the fact that it lacks the comb filter shared by the S9 and X9. It was entirely hand built from hand picked electronics and weighed a massive 36 kilograms. Many argue that the newer X9 was a more capable MUSE player but that the X0 had superior performance with standard NTSC discs. Nonetheless, the X9 remains the more popular of the two models, as it includes the newer comb filter and is a dual-side player, meaning that double sided discs don't need to be manually flipped over in order to be played through. - Wikipedia - Laserdisc
X0 (as in "zero") Project