You're comparing a peak output level with a nominal input level. I'd be willing to bet that the 2450's output will clip before the input does.
The input sensitivity for an amplifier is the input signal level that results in full rated output. If the input sensitivity of an amplifier is +4dBu then that is the input signal level that would result in the full rated output of the amplifier.
That is different than the rated maximum input level for the amplifier and most amps will accept signal levels well above that needed to create full output. Addresssing those differences in level, the typically higher maximum input signal level to the lower level needed for full amp output, is one reason why you often use the amplifier's input attenuators. If you have a +22dBu peak input signal and the amp's input sensitivity is +4dBu, then having 18dB of attenuation at the amp input would seem to match the peak input level to the full amplifier output.
The alternative is to provide that same attenuation via a fixed pad located between the amp and prvisuos device or to reduce/limit the peak output of the device before the amplifier (provided you are affecting the actual analog output).