Q: Looking at the specs of the diamon 112 it shows the max sustained spl is 123 and the max output is 133db. I would have thought 6db down from max would put the sustained output around 127db. Is this box capable of that output at all or really maxes at 123?

The DiaMon doesn't attempt to be a full-range box, so it can provide plenty of SPL in it's role as a mid-high cabinet. I expect the RCF TT-22 offers response that goes a little deeper given its size and weight, which would explain why its maximum output would be slightly lower.

The background on the specs for the DiaMon is that although the peak output was very high, it's sustained output was limited by the DSP to prevent excess heat build-up in the coil.  This is why the peak output and the sustained output are more than the standard 3dB apart. It can do that peak output, but it can't sustain that output long-term safely. In order to provide customers with realistic expectations, we rated it at the limited SPL for sustained output.

The key is not to have the cabinet running into the limiter all the time. It will be able to provide great dynamic sound quality if the dynamics remain in the signal. That done, the peak SPL is achievable and the sustained output is significantly less relevant.