The 845 mono block is one of the very best amplifier we ever manufactured. The mono blocks are a monster weighing close to 80kg each. It operates at a deadly voltage of over 1200v (DC) and the tube filament consumes massive current. It was a herculean task to manufacture these power amplifiers and it was a very limited production. Even after 10 years of ownership, the owners have no plans to upgrade anytime soon. The sonic of these amplifiers are absolutely stunning.