But if you don't intend to upgrade the speakers, then there's no sense in wasting the money on a beefy amp.

Oops. Meant to include that point.

But, just to clarify, a 400W amp has no more facility to blow your speakers than a 30W amp. In fact, as I understand it, a 30W amp might have a greater chance since it's more inclined to clip when driving speakers that need more power than it can deliver. Right?