Not only was the guitarist a founding member of the hugely influential Neu! and Harmonia, he also belonged to an early pre-Autobahn Kraftwerk line-up, as well as collaborating with Brian Eno.

This makes the relative obscurity of Rother's solo albums outside Germany (where they proved far more popular than his seminal but hardly commercially successful output with Neu!) a bit of a mystery. At a time when every bit of noise generated by any freak who once bashed a bit of bongos at a lysergically motivated jam session at Amon Düül's commune is lovingly repackaged and re-contextualised, Rother's solo works have remained relatively tricky (and costly) to acquire. The consistent high quality of Solo - which collects Rother's first four solo albums, originally released between 1977 and 1982, alongside some fairly inessential previously unreleased material - makes the international sidelining of these records even more mystifying.

To be fair, we're not dealing with the groundbreaking innovation of, say, Neu! 75 - inspiration for everyone from Public Image Ltd to Primal Scream, and onwards to LCD Soundsystem and anyone who might be currently locating the kind of cyclical, locked-in groove that tends to get labelled ‘motorik’ - here. Freed from the combustible personal chemistries of Neu! (and lacking the proto-punk bile of drummer Klaus Dinger), these purely instrumental records find Rother exploring his softer side. In many ways, the recipe is similar to that sampled on Neu!'s three albums: construct a simple, graceful melody, add a protean groove, repeat until maximum hypnotic impact is reached. However, the lingering mood is somewhat warmer and gentler than on those distinctly frosted-over masterworks.

That doesn't mean that Solo translates into bland muzak, however. Although these albums are sufficiently housetrained to work as pleasing background music, there's plenty of alluring detail and not inconsiderable amounts of beauty to sustain attention. Take the title track of Rother's solo debut Flammende Herzen (from 1977) as an example. As Rother keeps scaling the deceptively plain guitar melody ever upwards from its minimalist foundations, it’s difficult to think of another track that manages to combine humble intimacy with unabashedly epic grandeur with such grace and deeply affecting beauty.

From there on, standards rarely slip. There are tracks here that are grand and dramatic enough - check out "Katzenmuzik 7" (off 1979's Katzenmuzik) - to soundtrack heroic and noble track and field sporting feats or successful space mission launches, as well as spots of becalming ambient soundscaping. By the most recent album on the box, 1982's Fernwärme, keyboards start to take over from guitars, leading to electronic explorations that hark back to Rother's work in the proto-electronica pioneers Harmonia. Krautrock afficianados will be thrilled to note Can's drummer dynamo Jaki Liebezeit features on all four albums: his minimalist precision and the metronomic, impeccably well-timed embellishments help tracks like "Stromlinien" off 1978's superb Sterntaler build a formidable momentum without the music ever sounding remotely aggressive or assertive.