“It takes a special chemistry for any residency to endure for 20 years. As much shines through this celebration of the monthly get-together hosted by the sibling duo Sara and Sean Watkins at LA’s Largo nightspot. As co-founders of the hugely successful (and innovative) bluegrass band Nickel Creek, since 2002 the Watkinses have attracted a stellar roster of friends and fellow travellers to revive ye”