Help please

You are sure the preamp is working correctly?
Can you try the preamp in a friends system?

It sounds like something is out of phase. Reverse the speaker leads on one speaker and see if that helps!

I think lak and yogiboy make good points. 
Please verify that you have confirmed those points.

If switching speakers left and right and the problem still exists in the same speaker then concentrate on the speaker. You could have a blown cap or resistor.

If when switching the speakers the problem remains in the original channel then concentrate on the preamp.

ozzy

Update 
I have been emailing Jim Thompson all day , owner of Eggleston works speakers. What a great gentleman. So i put my Dynaudio C-4 speakers back in and everything is good again, so i told Jim what im hearing different and we are going through it step by step as i have something wrong with the Eggleston speakers. I still dont know what started all this mess, but with the new amps and my back up pre amp in there its working for now. Thanks to everyone for your suggestions.

Maybe a bad time to mention this but I will be doing a review of my new amps (Theta Prometheus mono blocks) they seem to be quite good.