Originally Posted by bobcruz
Original speakers were almost certainly two 8-ohm speakers in parallel, so if you did the same thing with 4-ohm speakers you've been very, very lucky to still have a working amp. Do not record anything -- rewire them to series and see if that takes care of it.
If you hooked them up just like the old ones were, you may have given yourself a 2 ohm load. This couod have cooked the amplifier, or, if the amplifier survived, it may have cooked the voice coils from the increased power, or a little bit of both.
While you take it apart to wire it in series, push on the cones to check for any rubbing/scraping sound.
Report back what happens.