My Marantz DV9500 never had problem with any dvds, no matter it is dvd-original, dvd-5, dvd-9, dvd-china, or even dvd-r. All other audio discs also had no problem e.g. cd-r, cd-clone, cd-china, sacd, dvd-a.
Strange thing is my Matrix Mk.2 dvd player, which is well-known for its reading capability, cannot read some dvd-china or dvd-5, but DV9500 can read through smoothly.
Not sure if the modifications i made could help (i did internal ac cable re-wiring, superclock3, SDI board).
