Almarro 205 mkll

I did not read this in its entirety but perhaps there is something in here that can help you...
https://6moons.com/audioreviews/almarro4/mk2.html

Isn't this an integrated amp (mine was)? It's designed to accept line-level voltages not for connecting to a pre-amp. 

yes  it is an integrated but thought this info would be useful when selecting a phono preamp. Am I mistaken?

From my limited knowledge, The output from a phono box is "line level". I believe the standard is: RCA outputs 2 volts and XLR is 4 volts. Your integrated doesn’t know if the signal is from a CD player or a phono preamp. It just wants it to be the standard voltage so it can processes it normally. I don't think impedance comes into play like it does between preamp and main amp.

I think the input impedance of your amp is the resistance value of the volume pot (Based on the link provide by zkidd).

https://6moons.com/audioreviews/almarro4/schematics.gif