Anyone in or near Ann Arbor?

I gather you are connecting the unknown phono stage to a line level input on your Allnic integrated.  Yes?  If so, it's highly unlikely that your apparently odd result has anything to do with the interface between the phono stage and the Allnic, assuming nothing on either end is grossly defective.  Most tube devices offer a high input impedance which is compatible with both tube and solid state source components.

The Allnic has an unusually low input impedance of 10k ohm, which I discovered after the fact.  The unknown solid state phono pre I believe has an output impedance of around 2k ohm.  There is nothing defective with the Allnic.  If I could drop this phono pre into another system it would likely be fairly apparent if it’s a matching issue in my system. 

Contact ozzy here on Audiogon or you could take the phono-preamp to an audio store in Ann Arbor and try it there.

Hello,

You are welcome to bring it over to my place, in Novi, for a listening session. Email me through Audiogon and we can exchange contact information.    

David 

you may want to consider an RIAA EQ playback LP and measure the output voltage of your phono stage for each freq before you do anything. Once you have a flat response, then you can decide if a change is needed.