Stunning cable comparison

Although not a veteran audiophile, my ears are pretty good on details. Therefore, I'm stunned as to what I'm hearing when comparing several different cables with my system. I have a HT setup with a Classe' SSP-25 which has a good analog bypass for stereo listening. My two channel amp is the Innersound ESL with ML Aerius fronts, Cinema center and some Mirage omnipolar rears with a B&K 4430 for the center and rears. I also use a Mirage sub and a Sony progressive scan DVD player which sounds really good with CD's.

Now here's the mystery. When purchased new from my local Tweeter (gasp!), the salesman hooked me up with Monster cable saying I didn't need much more since I was using a Yamaha receiver. Now that I have upgraded to separates, I am beginning to try other cables in search of better two channel sound. My first "upgrade" was Signal Cable shotgun biwire cables. They are about the same as the monsters in sonic detail (I'm having trouble getting detailed mids and highs). The choice of Signal Cables was an attempt to work my way up slowly and hopefully enjoy the ride as I audition better and better (subjective) cables. Also, I installed Signal Cable IC's and PC's which have made a remarkable inprovement to my system. Much tighter bass and more detailed mids and highs. Night and day from the Monster IC's that Tweeter sold me. OK, finally to the mystery. I recently decided to "upgrade" cables again and researched the gon for folks using the ML Aerius and found that many used Acoustic Zen Satori's and were satisfied. Long and short of it...I purchased a near new set of 8' spade/spade Satori's and cannot believe what I am hearing. The Monsters and Signal Cable wires are much more detailed with cleaner and tighter bass. Go figure...Can anyone explain why $600. cables don't sound as good as $100. cables??? One other note. I am still using the original brass plates that came with the ML's to connect the high and low binding posts on the speakers. I have tried using bare 8 AWG wire but it doesn't sound as good as the plates. Will a good set of jumpers help and if so, any recommendations as to which ones to purchase? BTW, the sound is now acceptable but I still want to improve it more if possible. It sounds great in HT mode. Just lack a little in stereo. Also, I know all of my connections are being made properly.

Thanks for any intelligent responses/recommendations.