Will Digital ballast work with diffrent watt bulbs?

I am thinking of buying a 600w digital ballast because my magnetic one gets to hot and gives off a burning smell :/ (been like that since it left the store)...

What i want to know is will it a 600w ballast dimmed down to 400w work with a 400w bulb or will it only dim down a 600w bulb?

Also any idea what to get... i was thinking lumatek or galaxy but not sure if they work in the UK

Take that ballast back and show them what its doing.

Pretty much any problems with a magnetic ballast are fixable and I know a lot of hydro stores do so in-shop for a small fee. Hell, are you sure your ballast isn't still under warranty? You need to do something about this though, because the burning smell is not a safe one to have. I'm not sure about putting a 400W bulb in the digi ballast if its kept at 400w as well, a big part of me thinks it'd be fine but there's also a small, rational voice that thinks it would't be a good idea.

Dimmable ballasts are meant to 'dim' the wattage from say '1000' to '400'

My magnetic ballast is only about 3 months old.... i thought the smell was because it was a cheap ballast but if its not because of that then i think i might give them a call and get it swapped.... the thing gets so hot you can touch it