I understand this is an older thread but I wanted to provide some insight (as I know many folk find these threads via a Google search). I would have to honestly say that in my experience in dozens of amplifiers and preamps that I've tried them in, the Miflex beats the Odam in every category that is important to me- more organic tone, more transparency and a more natural midrange. I think the Odam lack good lower midrange/upper bass delineation and I simply cannot enjoy them over time- far beyond 300-500 hours, so burn in is not a concern. The Odams do seem more extended in the highs and deeper in the bass, but I have to try to convince myself that this is better. With the Miflex (once adequately burned in) everything simply sounds more right/real/correct to me. Of course, YMMV but I do not care for the Odams.
All the best, Aric