None of the best ones play both formats in fact the X9 only plays LDs, no CDs. I borrowed this info about the digital sound of LDs.
(Unlike DVDs, which carry Dolby Digital audio in digital form, Laserdiscs store Dolby Digital in a frequency modulated form within a track normally used for analog audio. Extracting Dolby Digital from a Laserdisc required a player equipped with a special "AC-3 RF" output and an external demodulator in addition to an AC-3 decoder. The demodulator was necessary to convert the 2.88 MHz modulated AC-3 information on the disc and convert it into a 384 kbit/s signal that the decoder could understand. DTS audio took the place of the PCM audio tracks, and required only a direct connection via Optical Audio cable and a decoder to be heard.)