Anyone try this way to wire your loudspeakers?

"ZD542 I presume based on the OP's post that he has tried standard shotgun config"

Most likely he did. I was just interested as to what the differences were.

I have a pair of Mirage M3si speakers and I do not intend to upgrade.

Zd542, the amp. is a SS McIntosh MC452 autoformer and yes, I did consider tapping in both shotgun pairs to the 8ohm binding post but as the new Macintosh binding post are great for banana connecters they really, really suck for spades and I don't think they will stand the stress of double spades. I picked up one pair of cables used on AudioGon in a 9/10 condition and the 2nd pair new from Canuck Audio and paid about $1,200 for each pair. Cardas has replaced the Golden Reference with some crazy priced heavy weight new cable but thanks to AudioGon
and a little patience some great Golden Reference cable can be had. As Philjolet suggests I will try reversing the 8 & 4 ohm taps but only after a few more "cigarettes in the silky after glow of the experience"!

"Good speakers use good wires."

Tell that to Spencer and Derek Hughes and legions of other speaker designers who have designed the world's finest speakers! The key to great sound is called "design," not "cable."

It seems to me that you (if the jumper wires are removed) you have changed the impedance of the mids/tweets as far as the amp is concerned. Have you tried swapping the leads between the 8 and 4 ohm taps to see what the diff is?