In 2009, songwriter and producer Tom Krell proved that R&B could be quiet, even subtle. In the beginning, Krell’s moniker, How to Dress Well, was also his mask—the artist released his first few EPs under the anonymity of the name. Now, five years after his debut, Krell is bold enough to show his face: His newest album, What Is This Heart?, features his sad-looking head on its cover. In a sense, the new album, with its melodic falsetto vocals, hand-claps, and bumping beats, is classic R&B. But Krell forgoes some of the genre’s more traditional elements; instead of slow sex jams or sensual crooning, Krell focuses more on ethereal reverb and spooky, vulnerable vocals. Like a volatile relationship, his music ebbs and flows between themes of love and loss. “I found myself feeling stranded, alone and depraved, and generally run the fuck down,” said Krell in a promotional interview. “While writing these songs, I was trying to learn to lose in a meaningful way and to sustain loss as a source of creative energy.” One of Krell’s trademarks is his use of fuzzy synth tones and distortion that sound better on speakers than on headphones. In concert, on the venerable U Hall sound system, they’ll really shine. Sept. 20 at U Street Music Hall. $15.