The SE and Sport have an integrated Amp already, and what you're after is the holy grail of IS Audio tweaking, a simple switchable Aux input.
There's a few threads on this, and there's a few modification options as well, but if you're not technically minded I'd avoid these.
There's a thread in here about an aux in adaptor being constructed by a forum member which may be of interest to you, although we're still waiting for it to appear (it'll sell like hot cakes when it does though)
JS