The rock band will headline The Fillmore on Feb. 15

Firefly darlings X Ambassadors are headed to The Fillmore Philadelphia on Feb. 15 with their new single “Joyful,” off their forthcoming album of the same name.

The theme behind the Ithaca, N.Y. rock band’s new song was inspired by blind keyboardist Casey Harris, brother of Sam Harris, the band's frontman.

Sam said he wrote the song (at least, superficially) about Casey; and the single was born from heartbreak Sam suffered, caused by someone close to him. But then Casey intervened.

“One day my brother sent me an MP3 of some chord changes he'd written and I started immediately singing the phrase " ... to be joyful," over and over again,” according to a written statement from Sam.

Furthermore, the frontman stated, “If someone like Casey, who I've watched overcome so much adversity in his life, can appreciate the beauty of this world, then I ought to be able to as well.”

X Ambassadors drummer Adam Levin dished on the band’s mission for 2018, why they’ve been wearing fancier clothing lately, and the newest thing he's joyful for.

What are your (or the band’s) top 3 goals for 2018? 

Our main goal, which we’ve already started doing, is to release the new music we’ve been working on for the last year and a half. Our second goal is to come to Philly and as many cities as we can to play these new songs for everyone.  It’s the best feeling in the world to see our fans' reactions to the new material. We want to continue to give back and promote awareness for the causes and charities we believe in.

What’s the latest thing you're joyful for?

It sounds corny, but we’re joyful to have the opportunity to write and share music with our fans. We are really lucky!

What was Casey’s reaction to inspiring “Joyful?”

Casey is very modest and likes to downplay how inspirational he is, but we never let him forget.

How would you describe the direction of the new album? How does that project differ from “VHS?”

The new album is certainly a departure from "VHS" and represents where we are now as musicians and people. We’ve been through a lot since we released "VHS," and that is reflected in the new album.

Will there be any guest features on the album?

I don’t want to give anything away. You’re just going to have to wait and see.

What have you introduced on “Joyful” the album that you hadn’t on previous records? 

As heard on the title track, we’ve added a lot more soul influence on this record, and especially in Sam’s vocals. 

Over the last year the band has slipped into dressier attire, especially in the video for “Joyful.” What inspired the decision to switch up your wardrobe?

While writing the new album, it became clear that the music was going in a new direction and we wanted our aesthetic and wardrobe to reflect that. We decided to step our wardrobe up a notch. Can’t blame us for being fancy.