So far, the verdict has been in the direction of Callisto, but I like the OTL sound (or lack of it) so I am open to the MP-1 also. For now, for a lower price, the Einstein serves me well, also in the sense that I hear more of my phono and amp upgrades. The grip on the speakers is excellent. Perhaps a bit too muscular, not as refined as some preamps, can't judge, but a big step up for me. Budget did not allow the others (or, ideally, comparing all three). Albert, you are right that I am drawn to the Io Eclipse sound, all the more so since I changed from a worn Lyra Titan to a new Atlas nine months ago. This really sounds excellent. For some reason (German engineering?), with the new preamp, I have especially loved the sound with new elektro music like the "Vermont" LP. BTW I thought that a one-box solution would give less heat, but that is not the case, The Tube runs very hot, perhaps the equal to a Callisto with one power supply. I measure 75 degrees Celsius at the top of the transformers, but Einstein support says don't worry. The preamp can be improved by a pair of NOS 6922 tubes for the relevant input, in my case, the Io phono stage, and perhaps a NOS au7. I will order some tubes, to try. For now, this is clearly the best I have heard, from my system as a whole.