Paul O'Neill said he went into a bit of denial over the realization that this winter is the 15th anniversary of his Trans-Siberian Orchestra.

"The evidence is all around me," the founder of the prog rock-meets-classical group said from his home in New York.

"Teenagers who saw the band in '99 are now in their 30s," he added. "Teenagers in the crowd weren't even born when we started the band."

O'Neill, whose group returns to the iWireless Center in Moline next week for its 11th performance there in as many years, is taking a moment to look back with this tour.

It's the swan song for "The Lost Christmas Eve," the TSO's full-length holiday opera that has opened its shows for the past decade-and-a-half.

"The whole point of TSO is never to get painted into a corner," O'Neill said. "We just found ourselves painting ourselves into our own corner. The band was in a comfortable rut."

From 2014 into the foreseeable future, he said, TSO will present more of a straightforward concert during the holiday season, albeit one that will include some of the "Lost Christmas Eve" elements.

"If The Who doesn't do 'Tommy,' they still do 'Pinball Wizard,' " O'Neill said. "It's healthy for the band. The audience seems to love the change-up. It keeps things interesting."

The time for any reflection or celebration of TSO's accomplishment, however, will be extremely short-lived when its two companies wrap up their separate tours in Dallas and Buffalo, N.Y., on Dec. 30.

For the first time, the group is playing a New Year's Eve concert, outdoors at the Brandenburg Gate in Berlin, for more than a million people.

"We got overambitious on this one," O'Neill admits. "Our usual modus operandi is to take a couple of months off after the winter tour and then do a spring or summer thing.

"But in a moment of insanity — but it seemed like a good idea that day — we decided to take three hours off and then hop the pond and do the European tour," he added.

The plans were solidified only three weeks ago, he said.

"Right now, everybody's working out the logistics and seeing how we can make it work," he said. "We just pray to the rock gods that we don't hit turbulence."

Although he promised each of the performers a night in their own beds, he had to backpedal and say, "You can sleep on the plane. We'll make it up when we get back to Europe."

A former touring rocker, O'Neill said making several European trips back and forth, both for publicity and to nail down plans for the New Year's Eve show and tour, likely will take their toll.

"That was hard when I was in my 20s. Now I'm approaching 60 and it really messes with my body clock," he said.

By both concluding "Lost Christmas Eve" and arranging the 11th-hour European tour, Trans-Siberian Orchestra keeps the same kind of attitude it had from the very beginning.

"Never get too predictable," he said. "That's how TSO was designed."