I know there is lots of cool information at http://www.crutchfield.com. I'm not a persion "in-the-know", but I am fairly good at physics and energy.

I believe it was at crutchfield where it illustrated the effects of hooking up more than one speaker to a channel. Basically, if you hook up the speakers in parallel (which I think would happen using the Y splitters), your amp see's one 2-ohm speaker instead of a 4-ohm speaker. Less resistance means more power drain I guess, and if you have a crappy amp you could burn it out. A lot of amps have a rating that says they are 2-ohm safe. As far as I know, you shouldn't try this unless your amp is 2-ohm safe.

The other case is if you hook up the speakers in series, which would create one 8-ohm speaker instead of a 4-ohm speaker. More resistance would probably mean less power to you speakers (I suspect it would reduce the effectiveness of your amp in half on the channel). Your sound would have "less power" I'd think, and may be noticable as weak and flat sound if you have a wimpy amp.

Anyway, I got all that from crutchfield. I'm no expert on sound equipment really. I suspect someone else could explain this better.

Kureg