Hi All,
a 7-disc set of Mozart piano sonatas, clocking in at ~406 minutes. It was an SA-CD, including multi-channel. My assistant and I still shudder at the ~21 hour QC on that one.
All told, it took about 3 years to complete (recording, editing, re-recording, more editing, schedules, more editing, ridiculous amount of Renovator processing, etc.)
Otherwise, a 10-disc DVD set of a series of live jazz concerts that only took about eight or nine days to master, etc. The 2-disc SACD version took waaay longer due to the extremely 'primitive' tools that existed for DSD/SACD back then (16 hours for an hour-long EQ render, etc.)
Cheers,
Graemme