Autoformer vs Speaker impedance Curve

I I agree with Georgehifi. Your noisy fan on your Classe CA-2300 was probably caused by dirty filters on the fan. You might want to check your filter. Cause the fans on all my Classe CAM-600, CAM-300 & two CA-2300 amps that I have in my dedicated HT room are silent and barely barely audible. My dedicated HT room is very well treated and get dead quiet when there’s nothing being played, and while it’s true that I have a very large dedicated HT room.

Which Classe Omega amp is it that you saw for sale? Was it the Omega stereo amp, Omega monoblock amps or the Omega Omnicron monoblock amps, which are lower end series of the regular Omega monoblock amps.
The Omega stereo amps are even older than the Omega monoblocks or the Omega Omnicron monoblocks.
I believed that the Omega stereo amps were first introduced in the late 90’s, whereas the Omega monoblock amps and the Omega Omnicron monoblock amps came out in early 2000s if my memory served me well maybe between 2001 to 2004 I think and remained in production until late 2000s around 2008 or 2009 or maybe even 2010.
Make sure you get the one from late production around 2008 or 2009. You can ask the seller for its serial # of the amp and once you have it, I would suggest you contact Classe give them the serial # of that Omega amp and ask them what year it was being manufactured.

Omega Mono Refrence purchased new in 2004

Thanks again both! Was just listening to “Interstellar” sound track. Can definitely hear the fan on soft passages.  I will clean the fan filter.

@73max

You might want to clean the fan filter.

In regards to the Classe Omega Reference monoblock amps that are for sale and were purchased new in 2004. There’s no way to confirm that unless you get the serial # from the seller and contact Classe and give them the serial # and ask them what year the amps were manufactured. The Classe Omega amps are still the best sounding amps that Classe made and are superior sonically to any Classe Delta series amps.
These Omega series amps are pure class A deigns whereas the Delta series amps such as your CA-2300 are class AB designs. Those Omega series gears were very expensive more expensive than the Delta series gears.m
The Omega Reference monoblock amps original retail price was around $30k or $35k for the pair when they were still in productions.
Sometime certain Classe dealers still are able to get V stocks of these Omega series amps brand new directly from Classe.
My local Classe dealer here had a pair of these new Omega Reference monoblock amps v stock brand new form Classe 2 yrs ago.

This statement ignores just how much loop feedback is needed to fully compensate for this sort of thing. We all know what too much feedback has the reputation to sound like.

20 db is plenty. The problem area with feedback is **moderate amounts** between about 4 db up to about 15 or so. Over that and the feedback is usually sufficient to make almost any amplifier act like a voltage source.

IOW George, the quote above was completely misleading. If you doubt me, read Nelson Pass' article on distortion and feedback:
https://www.passlabs.com/press/audio-distortion-and-feedback
Any of the amps that you recommend run 20 to 30 db of feedback! In this case you're trying to play both ends- when all the amps in question run large amounts of feedback.

Consider your bubble popped.