I doubt it was released in quad, since it was released in 1978. it would have been nice to have any ABBA recordings in true quad. But FWIW, Voulez-Vous seems to decode very well in SQ (just now listened to it after viewing a youtube clip entitled "ABBA out of phase stereo".) The chorus for Lovers Live A Little Longer reveals different background vocals in the rears which were initially obscured in regular 2 channel stereo mode.