as darker or richer than the purer but less full-bodied sound of other pianos, such as Steinway & Sons or Yamaha. On the Imperial Grand, this characteristic tonal quality in part derives from the inclusion of nine additional bass notes below bottom A. These extra keys were originally added so that pianists could play Busoni's transcriptions of J. S. Bach's organ works, which required the 32′ bass pipes (usually played on the pedal organ). As very little other music makes direct use of the extra strings, they usually contribute to the piano's sonic character not through being played directly but via sympathetic resonance, when other strings in the piano are struck, contributing additional body to the tone. Moreover, the bass notes of the Bösendorfer, including the extra bass keys, are very powerful, adding volume in demanding literature. Bösendorfer Kuhn pianos come with 10 Swarovski leaded-glass crystals inserted along the steel structure. The million-dollar Kuhn has 72 crystals installed under the strings. The rim of a Bösendorfer grand piano is built quite differently from that of all other grands. Instead of veneers bent around a form, the rim is made in solid sections of spruce and jointed together. Spruce is better at transmitting sound than reflecting it. This is perhaps why Bösendorfers tend to have a more delicate treble and a bass that features the fundamental tone more than the higher harmonics. There are also two other features of Bösendorfers that are shared with only a few other piano brands: one is a removable capo d'astro bar in the treble, which facilitates rebuilding of the instrument and, Bösendorfer says, provides greater acoustic separation from the plate, decreasing tonal absorption; the other is single-stringing, providing each string its own individual hitch pin on the plate instead of connecting it to a neighbouring string. This design may slightly improve tuning stability and is an advantage in case of string breakage. The latest development in the Bösendorfer range is the CEUS digital grand piano reproducing system, which incorporates a computer-controlled mechanism that records a performance on a digital storage medium (magnetic disk or memory chips) and plays it back. The requisite equipment can be fitted to most Bösendorfer pianos to allow the direct recording of pieces while capturing all the keyboard velocity data as a .boe file. Bösendorfer uses a proprietary format to record key and pedal movements as a digital file. Models Bösendorfer