You seem to be confusing two different things here. While it is true that Dolby Digital is a form of lossy compression, it is superior to the matrix encoding used to encode surround to two channels. I believe that the discussion regarding the PS3 has primarily been between the PCM audio with HDMI vs. the Dolby Digital audio with optical.
I don't know if the PS3 supports outputting 6-channel discreet analog output. I haven't seen any such cable.