Radio (Rounder, 2015)

While appreciating Rolling Stones, The Kinks, and Casey Kasem references, wouldn't a bluegrass song such as the title track here be strengthened by Monroe, Scruggs, and Ray Davis touchstones? Not when one realizes that this album has less to do with bluegrass than any previous recording by Steep Canyon Rangers.

Having seldom worked with the same producer twice, one is not longer surprised by evolutionary progression in the SCR sound. Versatile, as their work with Steve Martin and Edie Brickell has proven, the nimble five-piece, mostly bluegrass outfit is now a six-piece Americana workhorse.

Circumnavigating the breadth of Americana influences, of which bluegrass is but a part, SCR are no longer the band that once recorded slightly off-center bluegrass. Even as recently as their last album, 2013's outstanding "Tell The Ones I Love," their bluegrass spirit was front and center.

They now appear as a stout, multi-textured band following a different path, and with Jerry Douglas sitting in the producer's chair, their sound only minimally resembles even the broadest definition of bluegrass. Some songs - "Blow Me Away" and the instrumental "Looking Glass" - are minimally recognizable as bluegrass; more frequently, you hear elements of a lot of things - blues, rock, country, and even jazz - and somewhere in the melange are faint echoes of a bluegrass whisper.

None of which is to suggest that this isn't an incredible Americana album.

Energetic and propulsive, "Radio" is an album that only occasionally takes a breath, as on the lovely "Blue Velvet Rain." Perhaps with a bold eye toward the larger festival market, Steep Canyon Rangers have gone for a bold, acoustic rock and roll sound, and they have achieved it. Strong, completely enjoyable songs, "Simple Is Me," "Diamonds in the Dust" and "Break" are pretty far out there in structure and execution. "When The Well Runs Dry," "Wasted" and "Down That Road Again" are terrific country songs cultivated by appealing mandolin and fiddle elements.

Steep Canyon Rangers continue to be one of the most lively acoustic bands working, recording well-written, thoughtful original songs that go to unexpected places; there are few bands like them. Unless "Radio" is a 'one-off,' however, it's not sure we can still call them bluegrass.