Soundstage gone


Hi guys,
I was really happy with the sound I had from my system until I decided to upgrade my turntable to MC stage. What I had: Linn LP12 with Lingo 3, Akito tonearm and Adikt MM cartridge. The amp is MA2275, speakers B&W 802. Recently I upgraded TT with Radical power supply, Urika MC internal phono stage, Ekos tonearm and Kandid cartridge. My amp has only MM phono stage, so tried to plug the cords from the table into other available inputs: CD2, tuner or DVD. The sound was amazing but the soundstage almost gone. I was shocked. There is no more splitting sounds between speakers and all the records plays as mono. Is there a way to fix that? Forgot to mention: I have a dedicated power line and my cables AQ Hurricane, AQ Oak.

lviv
I know this is going to sound crazy but is there a way that you can get another cartridge from the dealer and see if there is any improvement?  That way, at least you have reduced one of the variables in this equation.
OP feared the outboard phono pre would require "putting two phono stages together." This is exactly what it would AVOID. As sgreg1 points out, outboard phono pre should enter AUX or whatever else is available, NOT the amp's own phono stage. If this doesn't clear up the trouble, you've ruled out the diagnosis of defective phono in the amp. 
There is no more splitting sounds between speakers
Maybe the sound is so good, the speakers disappeared!
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Do an xperiment.  It will cost you about $150. 

Buy a Schiit Mani, configure it for MC and feed the phono out into the Mani, instead of the Urika.  Feed Mani output to your amp.  If the sound improves, it is the Urika's problem.  If the sound is the same, it is the cartridge's problem.