I was just reminding OP about his unit's trim controls. Cannot use phono 1 or 2, RIAA EQ happens at those 2 inputs.
AUX is good for ANY line level device, and AUX has the trim control which OP can adjust as/if needed relative to variable outputs he asked about.
btw, the trim controls are not accessible if the unit is in a case. You need to pull it forward a few inches, they are top mounted near the front left. They exist to equalize signal strength phono 1, phono 2, aux so no volume change is needed when changing inputs.
I do not know about streaming, or using tape inputs, or tape input being preferred. You cannot use Tape HEAD, as tape eq signal boost is involved for that input similar to Phono.
If you use tape monitor in, then you need to use Tape Monitor on the face of the unit to use whatever is in that input.
DIFFERENCE: AUX and Tape Monitor are both 0.3 volt input sensitivity. Tape Monitor Input Impedance is 100k ohms; AUX input impedance is 200k ohms