I tried both with the same gear and on the same day. The Magna is punchier and maybe a bit smaller sounding. It really hits hard. The Immains is a bit less on the punchy side (more than the CA-1a) but the soundstage is bigger, and really drew me in. Infact, after 1 or 2 listens on the Magna I wanted to go back to the Immanis.
Saying all of that, Danny M at RAAL who has genius level hearing told me that he liked the Magna more. For me the Immanis was an easy choice.
The Immanis is sonically closer to the SR1a and the Magna was more like a CA-1a on steroids. You cannot go wrong with either.
We listened to the 2 phones using my RAAL VM-1a tube amp that I think is even better than the stock version (different tube). A RME DAC and a direct computer connection to the DAC was used. Even with this inferior streaming setup it was some of the best sounds I have ever heard.
BTW - I just sold my office LRS+ speakers. This gets me 1 step closer to the Immanis. Though I lost my office space I will end up with better sound.