Astolfor, I am a little confused by your post. It seems you are saying you like the Zesto phono stage better than the Steelhead, but you bought a Steelhead. Then you go on to list the ways in which you think the Zesto (presumably you're referring to the Andros II version) outperforms the Steelhead. Except some of your claims are questionable and others seem just incorrect. If you just like the sound of the Zesto Andros over that of the Steelhead, that is fine and dandy. I am not challenging you on that score.
Noise. You say the Zesto is quieter. Is that based on published specifications, independent lab test results, or your own personal impression based on listening to music on each unit? It would surprise me if the Zesto is really measurably quieter than the Steelhead, because the Zesto is an all-tube unit, using all 12AX7 type tubes, whereas the Steelhead is a hybrid transistor/tube design, using high transconductance tubes. Zesto does derive its MC stage gain by using built-in SUTs, so it is conceivable that it could measure lower in noise, if you compare it to the MC sections of the Steelhead. But even the Steelhead uses autoformers in the output section of its MC circuits. I would guess that on a practical level, both units are "quiet". The astute listener would not likely reject the Steelhead for being noisy.
Flexibility. The Steelhead offers one pair of MM inputs and two pairs of MC inputs, selectable from the front panel. Capacitance and load resistance are adjustable for each pair of inputs selected, on the front panel. Gain is selectable in 5-db increments from 50 to 65db, for any of the three pairs of inputs. (You know all this, because you own one.) The Andros offers one pair of inputs each, MM and MC. The range of slectable gain is similar to that of the Steelhead. I don't see anything in their on line literature regarding how one would alter load capacitance or resistance. Nor do I see controls for those parameters on the front panel, in photos. So there is no basis for stating that the Andros is more flexible than the Steelhead. Again, if you like the SQ of the Andros over the Steelhead, that is the point of making a change.
Finally, probably because it uses only 12AX7 tubes throughout, which have a very high plate resistance, the output impedance of the Andros II is listed at 10K ohms. This is very limiting as to what the Andros II can drive. Driving any downstream component with less than about 100K ohm input impedance is likely to result in some high frequency attenuation. I see now that the Andros II has been superseded by the "Andros II Deluxe", which uses one half of a 12DW7 as an output stage, affording a much lower output impedance of 150 ohms, which is good. If you do buy a used (or new) Andros, make sure you get the "Deluxe" version.