Among the current generation of chart-topping pop artists, you might think that Silk Sonic, the Grammy-anointed duo of Bruno Mars and Anderson .Paak, would be the least susceptible to nü-metal nostalgia. Silk Sonic’s whole thing is smooth ’70s-style good-time music, not losing your sight, losing your mind, wishing somebody would tell you you’re fine. But if you search hard enough, you might find evidence of Bruno Mars banging System Of A Down and Incubus, or of Anderson .Paak moshing at a sparsely attended hardcore show in Oxnard. So maybe it’s ultimately not that much of a surprise that the group, during a surprise pop-up aftershow last night, took on Papa Roach’s immortal 2000 depression-rager “Last Resort.”