I'm a bit late on this one, unfortuately there was no one to tell me the difference between the two so I had to just fork out the money and try it, here is my take on it:
I have the Rotel RB-1090 amp and Rotel RC-1090 pre-amp. Things got the better of me and I ordered the Odyssey Mono Extremes and the Tempest Pre-amp. The Odyssey Momo Extremes took a very long break-in for me but finally did. The sound is nice but I was disappointed and went back to the Rotel RB-1090 and RC-1090. The Odyessey just didn't have the musical magic sound of the Rotel sound. It's not an upgrade to Rotel's top line. There's a review of the Odyessey Mono Extreme and Rotel RB-1090 and they prefered the Rotel's creamy airy smoother sound. The Rotel is just as detailed as the Odyssey but love the soundstage and imaging of the Rotel midrange far better than the Odyessey. After two years, I sold my Odyssey Mono Extremes and Tempest to a friend. He still has it but now is looking for a nice used Rotel RB-1090/RC-1090 to change to the Rotel sound.
I have the Rotel RB-1090 amp and Rotel RC-1090 pre-amp. Things got the better of me and I ordered the Odyssey Mono Extremes and the Tempest Pre-amp. The Odyssey Momo Extremes took a very long break-in for me but finally did. The sound is nice but I was disappointed and went back to the Rotel RB-1090 and RC-1090. The Odyessey just didn't have the musical magic sound of the Rotel sound. It's not an upgrade to Rotel's top line. There's a review of the Odyessey Mono Extreme and Rotel RB-1090 and they prefered the Rotel's creamy airy smoother sound. The Rotel is just as detailed as the Odyssey but love the soundstage and imaging of the Rotel midrange far better than the Odyessey. After two years, I sold my Odyssey Mono Extremes and Tempest to a friend. He still has it but now is looking for a nice used Rotel RB-1090/RC-1090 to change to the Rotel sound.