Just to be clear, the Classe stack I spent time with was the Delta Series:
Delta Stereo - Classé Audio (classeaudio.com)
Delta Pre - Classé Audio (classeaudio.com)
I would think twice about putting an amp like this or, for that matter, any powerful amp in a rack with glass on the front or anything possibly preventing good airflow or proper ventilation. This Delta operates in pure Class A mode for the first 12.5 WATTS. I'm no expert on this but I think that's why the fan.
Again, I stood right next to this thing when there was no music playing and it was dead silent. No fan noise. Now, would that change over time? Don't know. A good question to ask or do some research on.