Bass man Steve Mackey brings the bottom line to tracks by some of Nashville’s most celebrated artists. It’s clear why he’s a country stalwart; on Luke Combs’ “Forever After All,” he anchors the twang with groove and gravitas. He’s also the guy adding low end to the grease and grit of Delbert McClinton’s roadhouse rocker “Right to Be Wrong” and punctuating the fluid mix of blues, R&B, and Americana on Robben Ford’s earthy ballad “Wild Honey.”