Whereas most drum 'n' bass acts are identifiable by a signature sound (Goldie, LTJ Bukem, and the like), Spring Heel Jack doesn't really have one, which makes its music all the more interesting. The duo's inventiveness may be a result of pedigree: When he's not with Spring Heel Jack, John Coxon picks up a guitar to play psychedelic chamber music with Spiritualized, while Ashley Wales brings jazz and classical training to the fore. That's why Treader, the band's fourth album, has almost nothing in common with most drum 'n' bass records -- it's a mélange of styles that bump up against one another like paintings in a crowded gallery. Some tracks feel like science fiction soundtracks ("Winter"), or play with jagged, unfriendly beats ("Outerlude"), or attempt full-scale beats-per-minute assaults ("Blackwater"). But most of the record is beatless, driven by empty spaces and impressions of great distances. Treader finishes off with "My Favourite Things" and "Climb Ev'ry Mountain," drastic deconstructions of familiar themes from The Sound of Music. It's hard enough to dance to most drum 'n' bass -- you sure can't dance to this.The collection of even less typical Spring Heel Jack tracks known as Oddities lives up to its title. This experimental outing collects some of the most bizarre and abstract aspects of Spring Heel Jack. A spoken recital from William S. Burroughs is underscored by some ominous sax and stalking vibraphone on "The Road to the Western Lands." A wordless, almost formless "cover" of Spiritualized's "Shine a Light" lingers over a succession of organ chords as climax and denouement are ignored. Disorienting and difficult, "Trouble" sounds like a nature travelogue through the Galapagos -- after all the animals have been replaced by tyrannical cyborgs. "Piece For Six Turntables (Version 4)" is the oddest oddity of all -- at times sounding like a "Piece For LaMonte Young" -- using strings and strange things to pay respects to the avant-garde father figure. Fifteen minutes of strange sounds indeed -- like ball bearings rolling down a 20-mile-long water slide. Coxon and Wales are two vanguard musicians working in a genre that's by turns innovative and suffocatingly restrictive. Spring Heel Jack subverts the entire formula, turns drum 'n' bass upside down, and starts taking down the chainlink between classical and dance music.