Mascis is unquestionably best known for being the frontman of the highly influential rock band Dinosaur Jr., which he founded in his native Amherst in 1984, along with bassist Lou Barlow and drummer Emmett ‘Murph’ Jefferson. That same lineup of the band continues to record and tour today, having released their latest album, ‘I Bet on Sky’, in 2012, but the band were inactive between 1997 and 2005, and spent some time without Barlow - also known for his role as frontman of lo-fi legends Sebadoh - after a fallout with Mascis led to his firing in 1989.
Away from Dinosaur Jr., though, Mascis - one of the most recognizable men in rock, with his long white hair and beard and large spectacles - is also known for his solo career, the sound of which has generally been in stark contrast to his work with his band. He’s released four full-length records, in addition to two live albums, and has generally focused - especially on his most recent two solo LPs - on a mellow, acoustic sound that’s a million miles away from Dinosaur Jr.’s incendiary riffery. 2011’s ‘Several Shades of Why’ and 2014’s ‘Tied to a Star’ both have Mascis on reflective, laid-back form, cementing his status as one of the most versatile performers in modern rock.
Although he's probably best-known as a member of Dinosaur Jr., you're never going to get a belting rock show from the 'original slacker' when it comes to his solo stuff.
That said, I saw J Mascis a few years ago and it was such a great experience, just one guy and a guitar holding the audience for nearly an hour.
One thing that you wouldn't expect if you haven't seen him before is that J has a tendency to go from one song to the next with barely an ending, just letting the last chord ring out as he reaches for his capo or re-tunes his guitar. It's kind of a surreal experience, as if he's practicing rather than performing and you're not quite sure if you're supposed to be there. All that is heightened by that fact that he rarely looks up from his songbook to the audience but again, J's a slacker.
If you can accept that, and as a fan that's what you should be expecting, then J's awesome live, from strumming his own brand of lullabies through to blasting out a guitar solo the guy rips it, all while looking somewhat indifferent to whether he's even hitting the right notes.