The venerable German quartet Kraftwerk returned to Chicago tonight, the first time in seven years. No single group has influenced my listening tastes more than Kraftwerk and so seeing them live is always a treat.

I was struck by a few things tonight. Though Kraftwerk is praised for its groundbreaking style and influence on hip hop, industrial, and electronica, their style is often denounced (and parodied) as stiff, unfeeling, and immutable. It is true that the energy from the stage doesn’t come from band members doing Townsend windmills. But in fact if you consider Kraftwerk’s output not so much songs as themes (leitmotif seems the most apt word here, ja?) which are reworked and tweaked over the course of decades you see that they are in fact quite dynamic as artists. Consider that there are only a handful of themes in their ouevre — transportation, fame, energy, human-machine integration, computing — and that each has evolved either by incorporation into new songs (Tour de France into Aero Dynamik), by digitization and reworking (The Mix),or by considerable updating (Tour de France into Tour de France 2003). A good example is the way Radioactivity has evolved from a paean to Marie Curie to a polemic against nuclear energy.

The live show is extremely nostalgic. As pathbreaking as Kraftwerk is their live visuals contain long sections of period-specific artwork, vintage video, and command-line-aesthetic computer graphics. In fact, the band has never actually been about the future, though their subjects are often futuristic. Though they are all digital now, the aesthetic of Kraftwerk is still firmly rooted in sensibilities of the past. This is atypical in their musical genre. But then, they pretty much invented the genre, so they’re entitled.

I am embarrassed to admit that after 25 years of listening to Kraftwerk and attending three live shows I only tonight noted the irony that the Most Sampled Band in History actually invented the sample well before digital recording made it possible. Rather than pre-record sounds of everyday life Kratwerk usually imitates them. The clank of a train hitch, the crank of a bike wheel, the Dopplery overlap of horns on a highway — all these things are imitated using sounds and parameters from the synthesizers, rather than samplers. Call it mimetic synthesis, low-fi sampling. Call it royalty-free.