According to the official Trans-Siberian Orchestra website, band founder Paul O’Neill conceptualized the group like this:

"Basically I was building on the work of everybody I worshipped: the rock opera parts from bands like the Who; the marriage of classical and rock from bands like Emerson, Lake & Palmer and Queen; the over-the-top light show from bands like Pink Floyd ... I always wanted to do a full rock opera with a full progressive band and at least 18 lead singers."

EIGHTEEN LEAD SINGERS!

To me, “18” is the number of oysters on the half-shell one orders as an appetizer, not the number of vocalists fronting a band.

But what do I know about prog rock?

Diving deeper into the band’s website, it seems they have TWENTY singers! And you can see and hear them all as they crowd a grandiose stage set Sunday during the T-SO’s matinee concert in the Mohegan Sun Arena. Assuredly, the rest of O’Neill’s original vision will be in play, and it’s proven to have been a multi-platinum, top-level draw over the years. For the Sun show, the group is bringing back their popular and seasonally appropriate “Ghosts of Christmas Eve” production “plus greatest hits and more.”

How can Santa hope to follow this? He doesn’t even have 20 reindeer.

Trans-Siberian Orchestra, 3 p.m. Sunday, Mohegan Sun Arena; $71 and up resale; mohegansun.com.