They all have optical and/or coaxial output, which works fine for CD's and DVD's. But Blu-ray offers several new audio formats (Dolby Digital Plus, Dolby TrueHD, DTS-HD High Resolution, and DTS-HD Master Audio) as well as the option of having raw multichannel PCM on the disc. None of these can pass via optical or coaxial, as the only digital output that can support them (either as bitstreamed signals or multichannel PCM decoded by the player) is HDMI. DD+, TrueHD, and both DTS-HD formats all carry "core" DD and DTS tracks that can be passed via optical or coaxial, but it's a lesser quality - especially for TrueHD and DTS-HD Master Audio, which are lossless formats. To get the full benefit of those formats with a non-HDMI v1.1+ receiver or processor, you need multichannel analog (similar to DVD-Audio and SACD). That's one of the reasons that the BDP-83 is getting so much attention, as it combines Blu-ray, DVD-Audio, and SACD in a single chassis with a really good 7.1 analog section.