How many speakers and which taps are being used? How are you calculating the taps that will be used and how are the input level controls set? If you use low power taps, you won't get much SPL even from a powerful amplifier.

For those using the Crown CDi series, are you using Audio Architect, or just the controls on the front? If the latter, you really need to download the software and use Audio Architect.

The link shows the CDi amp sensitivity as 1.4V, for full output. If you're connecting a Sonos directly to the amp, you'll never achieve full output.

The link also has Audio Architect for you to download.

[Link: crownaudio.com]