I do not know of any DVD player that does this. If you have a 4x3 TV, the anamorphic transfer must be downconverted to fit into the 4x3 frame of the monitor. Of course, if your TV can perform the squeeze trick, you could leave the RP-91 in 16x9 mode. However, that is no different than any other player.
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The Malata N996 is able to do this. Set the player to output to a 16x9 TV and then use the x-y scaling capability of the Malata. Takes 16 clicks on the down arrow when in the x-y menu. It works perfectly without doing anything to the TV itself. At least it works on my 7 year old Sony 53" RPTV using S-video. And on top of this is does excellant PAL to NTSC conversion and plays all regions. If you have a 4x3 TV, buying the Malata is like getting a new 16x9 TV for free. The difference is dramatic on most anamorphic titles, including PAL titles.