Hey Alex,
No, it's not a stupid question at all. In a nutshell, yes... a receiver rated at 8 ohms per channel can drive a 6 ohm speaker. However, it's just not recommended. It also depends on the quality of the components in question. Some companies are fairly conservative with their ratings and recommendations. If the receiver is from a reputable manufacturer, than you may never encounter any problems with that match. But don't go any lower than the 6 ohms.
Again, just to clarify... it can be done, but it's not recommended.
sleeper.