A booming sad voice fills the air from the very first song.

“Hey now, letters burning by my bed for you.”

Melancholy yet so very strong, the voice of Hannah Reid of London Grammar is so powerful an instrument that you are forced to wonder if she could simply tour as an a cappella act and be tremendously successful solo.

But no. Given a bit of time at Monday night’s sold-out performance by London Grammar at the 9:30 Club, the gentle guitar of Dan Rothman and playful keyboards and drums from Dot Major swell under the vocals and provide each song with a full sound, as with the opener, “Hey Now.”

Still, Reid’s voice is inescapable. Halfway through the 10-song set, she understandably has to take a break and leave Rothman and Major with an instrumental interlude. The effect was not completely unlike John Lydon’s gargling breaks after a particularly powerful song by Public Image Ltd. The genres may be different but there is something similar in the use of the voice that requires the singer to reconstitute yet she strain her voice too much.

The result is dreamy and exciting. The audience is enraptured by the first song and totally submerged within several more songs. The crowd is hushed for a standout number “Flicker,” also from the band’s debut album, If You Wait, as Reid’s lyrics recall an image of a loved one in her dreams, snatched from the long journey of life’s path. London Grammar follow this up with the equally poignant “Sights,” a call to be strong in the face of adversity.

Nominally a trip hop act, London Grammar sound a bit unlike anything you’ve heard from many contemporary musicians today. That’s partly due to the range of influences that seep into Rothman and Major’s music. At various times, you can hear some blues, calypso, bossa nova. The various strands of sophistipop occasionally remind the listener of bands like Everything But the Girl, or even Bryan Ferry (who I personally hold responsible for the English love of calypso; he’s an easy target).

In the final third of the set, London Grammar cover Kavinsky’s “Nightcall” from the Drive movie soundtrack. London Grammar’s version brings its own atmospherics to the song, making it feel just as casually urgent as the original but with Reid’s distinctive voice, it seems even more persuasive. You’re left with an overwhelming sense of panic and relief perhaps? “Omigod, what have I done? What happens now? Oh wait, there’s nothing to fear?” It’s convincing.

The band closes the performance with their album’s haunting title track, an ode to unfulfilled desires. Again, Reid’s voice carries the audience across a wistful gulf of loneliness and longing, and the hope of addressing unfulfilled expectations.

Haerts is by no means the happiest band in the world but the Brooklyn-based quintet seem positively ecstatic compared to the English trio for whom they opened. The dreampop band plays their epic “Wings” early in their set—an analogy of no longer being able to fly after lost love. Vocalist Nini Fabi looked fantastic and her voice was awash in lush keyboards by Ben Gebert, resplendent guitar by Garret Lenner and strong rhythms by drummer Jonathan Schmidt and bassist Derek McWilliams.

The band sounds really great, although my concert companion suggests they are a little too “safe” in their performance as they shelter in place behind their instruments. While I certainly wouldn’t argue, all is forgiven as Haerts play through a really strong set of songs, closing with “All the Days,” a very evocative and moving ballad dwelling on lost love. I’m definitely looking forward to seeing them again soon—and thankfully they are playing at U Street Music Hall on Thursday, May 8 to accommodate me.