Does anyone know if this was all in Quad, or just 3 out of the 4 sets?
I have all 4, and only 3 are marked as SQ Quad.
Siegfried is apparently stereo.
(The Rhinegold, The Valkyrie & Twilight Of The Gods are all EMI SQ)

There is also a boxset version on ebay right now, and this also has a straight stereo only siegfried.
I was wondering if anyone actually knows the state of the set?