The MPA1100 is a high-efficiency professional power amplifier, with two independent channels, capable of delivering 1100 watts into a four ohm load (per channel), and substantially more power into lower impedance loads. Semi-toroidal power transformers one per channel are mounted in each front corner, as close as possible to the rack ears and rails. The rear panels are 16.9 inches behind the front mounting plane, so an extra rack depth allowance (i.e., more than 18 inches) will be needed to clear XLR or Speakon connections. The built-in fan cooling takes air in the rear, exhausting through front vents. Due to the flow-through cooling, amplifiers may be racked with zero clearance in between, which also helps support the weight. Rear support within the rack must be used in portable applications.