Did you like a cold coffee? buy kamira then. Preheating cant help you..Useless junk. You can use any sort of coffee and always get a foam. Only coffee will always be cold. 35ml..
Just use a citric acid solution and purge it after 30 minutes, like the Gaggia citric acid coffee cleaner. I use it on my channel for my Gaggia Classic Pro Espresso machine and for my automatic drip machine.