I have blogged about my aquisition of the new Nuova Simonelli Musica here: http://www.roaste.com/CoffeeBlogs/sontondaman/Nuova-Simonelli-my-new-toy . It had been great so far up to about one month ago. I had been a great steamer, producing luscious milk and very smooth espresso shots, definitely a very temperature stable heat-exchanging system as the shots had been very repeatable, responding very well to flush routine, dosage change and grinding setting.
Up to a month ago, I got a little hiccup with the Nuova Simonelli and that I think was probably my fault. The machine that I got was a pump in version and did not come with a tank. It must be directly plumbed into the water line but since where I live, I do not have easy access to plumb it in; I decided to use it temporarily anyway by feeding it with a bottle.
The reason I did this was because I did not have any trouble doing this with my La Marzocco Linea. With the NS Musica, there were really no problem for the first month or so feeding it water this way but one day, when I brew a shot of espresso, the shot cut off short of the volume I had set on the volumetric touchpad. After repeated attempt at reprograming the volume because I thought the machine might have forgot the volume I set it, I came to the conclusion that may be it is the way I'm feeding this machine water that allow air to get into the line and screw up the water mettering.
Now I decide that I must find a way to plumb this machine in without shortcut such as this as it might weaken the Musica's pump.