The partnership of Evans and Hall as an unaccompanied duo was an inspired one which produced two albums - this first one and the follow-up, Intermodulation. The two artists had much in common. For example, both were concerned to produce music which had beauty, and even refinement, of sound with no lack of musical substance. Both liked to play quietly, with an emphasis on subtlety and understatement, although they could also 'swing' infectiously at almost any tempo. Both also had years of experience as sidemen or accompanists in other people's groups and this made them particularly sensitive listeners, able to respond to and interact creatively with other soloists.
You can hear that kind of sensitivity and subtle interplay throughout this album, most obviously on the slower pieces but also on the fastest track, the original take of 'My Funny Valentine'. Listen especially to the way in which Hall's guitar fills in behind Evans's statement of the theme and then provides a driving rhythm under the pianist's improvisation.
My favourite track is Hall's 'Romain', a moody, rather sombre theme which inspires the most intense and emotive playing on the album. It has some particularly haunting interplay between the players and displays the 'singing' qualities they could draw out of their instruments, especially at the magical point where Hall's solo leads into Evans's. It's good to have the bonus of an alternate take of this number on the CD edition.
Undercurrent was always a rather special album; but it is superior as a CD, first because of its enhanced sound quality and the quiet background which this intimate, concentrated music needs, secondly because the bonus tracks on the CD provide the 'added value' of quality as well as quantity. The programme originally consisted, rather oddly, of five slow tempo tracks with one fast one. The addition of the mid-tempo swinger, 'Getting Sentimental Over You' and an alternate take of 'My Funny Valentine' creates a better balanced album, although an extra slow ballad from the session, 'Stairway to the Stars', is well worth having too.
It's an album which you can play, if you like, as a piece of chilled out background music which won't disturb the cat; but there's a lot going on under its polished surface to make it music to listen to, and to return to again and again.