Combine high and low outputs for Aragon 8008BB

I'm writing from Italy, so forgive me for my bad English...:-)
I've got an Aragon 8002 and it has 4 binding posts/channel, like the 8008. If you open it, you can see that signal cables are connected directly to 2 outputs. The signal goes to other 2 outputs by metal "stripes"
My amplifier sounds very good only connecting speaker cables to the outputs that are directly connected, otherwise sound is dark, slow and confused.
I can't explain why, but I've tried many times whit the same response.
Best regards
Sandro

There are no high and low frquency outputs on the aragon 8008BB. There are two sets of binding posts for bi-wiring.