Warthur
In the 1990s and early 2000s Pendragon weren't exactly a name known for wild experimentation - sticking firmly to the fairly accessible style of neo-prog they'd first unveiled on The World, the band soon became the subject of sniggering from some prog circles because of a perceived sameness to their albums.
However, after Not Of This World the band started to change up their sound, and the first herald of this sea change was Acoustically Challenged, a live set recorded for Polish radio in which the band retool their songs for mostly-acoustic instrumentation - Nick Barrett and Peter Gee on acoustic guitar, with Clive Nolan using his keyboards mainly to mimic other acoustic instruments. The transition works reasonably well, and in some cases taps into hidden reserves of beauty in some of the songs - I like the version of The Pursuit of Excellence on here much more than the original, for example. A gentle and beautiful album and a neat counterpoint to the grittier territory the band were about to delve into.