Robert Johnson is not synonymous with high fidelity and I, like most people, was turned off by the noisy, hiss-soaked sound of early releases.
Thats why I wholeheartedly recommend:
Robert Johnson - The Centennial Collection (Sony/Legacy Records, 2011, 88697 85907 2D1)
Recorded originally in the 1930’s, this 2011 re-release still isn’t perfect but you can enjoy the music w/o the background noise.