Anyone modded Classe CA300?

Depending on how much you want to spend and what your ear likes, I'd say the 300 is as good as most and better than others in its price range. As for mods, it is already filled with contemporary goodies.

Depending on the rest of your system you might be better off upgrading another part of your system. Is there something about your present sound that you don't like or want to improve upon?

Damping the ringing heatsinks helps a lot for a DIY simple mod.

In what way does damping the heatsinks change the sound? I have a CA-200 but I don't want to mess with it if I'm not sure what it will do... the amp is too mint to go sticking things to it :)

The CA200 may not have a big problem with this. The fins on the CA300 make a high frequency ping when tapped with your finger nail which my DR8 amps only make more of a dull clink sound when tapped. The transistors are mounted to the back side of the finned heatsinks. I used some strips of black painted MDF with brass cones upside down, set on top, used as weights run length wise just sitting atop the fins to damp the resonance. The amp did not run warm so it did not overheat the wood nor did the wood make the fins run appreicably warmer. I did find a reduction in glare and better reproduction of female vocalists along with a warmer more tightly focused soundstage.

Good one Rhljazz. Never heard or even thought of that before. I have a 301 and I will have to try some type of version of that tweak.