The M400 comes (and is better) in the T Version. Make sure you are watching what model you are looking at.
the original M400, the cube-shaped amplifier in which Carver introduced his magnetic field power supply technology, and the subsequent M400t version.
The original M400 sounded quite poor. The M400t sounded surprisingly good, and was certainly an excellent value in relation to its price and its power capability (200W/channel). The "t" denoted "transfer function modification," which meant in this case that it was designed to emulate the sound of a Mark Levinson ML2, which was a pure Class A megabuck monoblock amplifier of the time.