Well it's not just the $20.
For DCI Fathom events at my local theater, their left front sound channel has been out for years. So we get no sound on the left side. The surround speakers all work and the right side sound is good. But, it is absolutely silent on the left.
I've talked to people at the concession stand and they've done nothing. I even wrote to the management months before the event in 2019 telling them of the issue. Then I show up for the 2019 Big Live & Loud and the left channel was still out. It's infuriating.
Big Live & Loud has been held in different theaters in the same building and it is always the same, so I know that it is a problem on the receiver side not the theater side.
This started in 2014. The theater started the Big Live & Loud show and there was no sound. People ran to the concession stand, but there was no management around, so the popcorn girl went into the booth and started unplugging and plugging in cables until we finally had some sound. The left front was out then, but we were happy to hear anything at all.
Well since that day, no one has gone into that booth to fix the audio completely. They just don't care. So, I would rather not give them my money.