TimW
Major Contributor
I understand what you're saying and I think you're on the right track. You are right that you don't need to have the jumpers on the speaker binding posts. Because you are using the four connectors on the speaker side those jumpers are unnecessary but they also aren't hurting anything. If you think about it the speaker wires are connected together on the amplifier side so separating them on the speaker side won't make a difference but there's nothing wrong with doing that in this situation.
The way you have described moving the connections on the amplifier sounds correct to me. It is possible that the amplifiers will perform better with these connections corrected. You shouldn't have to change any settings for sending signal to the amplifiers since the cables designate which amp receives the left and right channel signals.
Another possible issue I just thought of is that your speakers are wired out of phase. When a pair of speakers are wired out of phase they will cancel each other out at some frequencies and sound very bad. To wire the speakers in phase you must make sure the positive (red) and negative (black) speaker wires are connected correctly to the speaker and amplifier for each side. Your speaker cables look to be home made and I don't see any positive or negative markings for the connector pairs. It is entirely possible that the speakers are not in phase with each other and there's no easy way to tell with those speaker cables.
Tomorrow when you're checking the connections, rather than removing those jumpers I would try reversing the polarity of ONE of your speakers. You can do this at the amplifier connections after moving the connections from the 8 Ohm outputs to the 4 Ohm outputs. After you change the connection at the amplifier, if things still don't sound right I would recommend swapping the connectors around on ONE amplifier with the positive wires connecting to the negative binding post and the negative wires connecting to the positive binding post. Again, if you try this, only swap the connection on one amplifier not both.
The way you have described moving the connections on the amplifier sounds correct to me. It is possible that the amplifiers will perform better with these connections corrected. You shouldn't have to change any settings for sending signal to the amplifiers since the cables designate which amp receives the left and right channel signals.
Another possible issue I just thought of is that your speakers are wired out of phase. When a pair of speakers are wired out of phase they will cancel each other out at some frequencies and sound very bad. To wire the speakers in phase you must make sure the positive (red) and negative (black) speaker wires are connected correctly to the speaker and amplifier for each side. Your speaker cables look to be home made and I don't see any positive or negative markings for the connector pairs. It is entirely possible that the speakers are not in phase with each other and there's no easy way to tell with those speaker cables.
Tomorrow when you're checking the connections, rather than removing those jumpers I would try reversing the polarity of ONE of your speakers. You can do this at the amplifier connections after moving the connections from the 8 Ohm outputs to the 4 Ohm outputs. After you change the connection at the amplifier, if things still don't sound right I would recommend swapping the connectors around on ONE amplifier with the positive wires connecting to the negative binding post and the negative wires connecting to the positive binding post. Again, if you try this, only swap the connection on one amplifier not both.