I have a pair of vintage 8 ohm full range speakers that sound really good on open baffle. Luckily, I just got another pair and thinking about adding these to the same baffle. What would this do to the sound other than making them more efficient. I know that wire 2 speakers in parallel will increase the efficiency level 3db more - but other than this I have no clue how would the sound change by adding this extra speaker in. I could cut a hole and add the speaker in but kind of reluctant to do this as I can not just undo the hole in the event of not liking the sound afterward.