A visit to the semi-imaginary McKittrick Hotel in Chelsea for a performance of Ghost Quartet will lighten your winter. Sound counterintuitive because ghosts are white and scary? Nope, because complicated Poe mixing plot aside these are Casper the friendly ghost ghosts. Double nope because some people are so damned talented that you can warm your psyche by watching them. Dave Malloy who conceived this show [and Natasha Pierre and the Great Comet of 1812] is one of them. So are the other cast members especially my soulful fave Brittain Ashford who combine great voices with the ability to play multiple musical instruments .  And the McKittrick Hotel has a real bar with just the right hazy twilightly diffused light. Here’s my final nope; they pass around bottles of Maker’s Mark during the performance.