When the volume was high, which people kept asking for, I heard a lot of upper mid-range/lower treble "pinging" off the walls. We also were all digital till Saturday afternoon, with a 5687 dying Saturday night. If you came by Sunday, when we were all vinyl (IO1, S4), and fully retubed with some really tasty tubes courtesy of a loan by Mark Margiotta, the sound improved markedly.

I wouldn't say the system was doing anything wrong beforehand; it was just telling some truths that were difficult to absorb.