Classical guitar for repertoire of all periods is sometimes critically viewed: Torres and post-Torres style modern guitars (with their fan-bracing and design) have a thick and strong tone, very suitable for modern-era repertoire. However, they are considered to emphasize the fundamental too heavily (at the expense of overtone partials) for earlier repertoire (Classical/Romantic: Carulli, Sor, Giuliani, Mertz, ...; Baroque: de Visee, ...; etc.). "Andrés Segovia presented the Spanish guitar as a versatile model for all playing styles" to the extent, that still today, "many guitarists have tunnel-vision of the world of the guitar, coming from the modern Segovia tradition". While fan-braced modern
Classical guitar type of repertoire is usually performed by guitarists who have particularly chosen to focus on the avant-garde in their performances. Within the contemporary music scene itself, there are also works which are generally regarded as extreme. These include works such as Brian Ferneyhough's "Kurze Schatten II", Sven-David Sandström's "away from" and Rolf Riehm's "Toccata Orpheus", etc. which are notorious for their extreme difficulty. There are also a variety of databases documenting modern guitar works such as Sheer Pluck and others. The evolution of the classical guitar and its repertoire spans more than four centuries. It has a history that was