Always amusing to see these ideas come round again… many attempts to introduce multichannel surround sound on vinyl and radio from around 1965-75. All died. Why? Hands up all those who can set aside a room with all those speakers (don’t forget the acoustic treatment) and an optimum position for just one! A few enthusiasts will always to to such lengths, but top quality headphones might be easier. And what does anyone intend to do with 120 dB dynamic range? If your room is reasonably quiet, the background will measure at about 40 dBA. Add 120 dB to experience the full whack and you get 160 dBA, louder than Concorde and definitely blood out the ears time. An ordinary CD will give about 100 dB dynamic range, though most seem to be produced with about 15-20 dB headroom, which brings the dynamic range down to a more practical 80-85 dB. Remember, you should not exceed 95 dBA for any length of time, especially at the higher frequencies - hence even the 50-55 dB dynamic range of a dolby cassette is not too bad from that point of view (the annoying problems with tapes were distortion and modulation noise). So, I am happy to pass on SACD - really no point!