Even if I'm totally uninterested at the subject, because I've always had the need of just one streaming at the time, I was curious to try something by my Solo4K. So this is what I tried:
1) I opened a (transcoded) stream by OWIF and it obviously opened a VLC session.
2) I launched iDreamX, a software for OsX similar to Dreambox, and I launched a second stream (again transcoded, too) and it opened a second occurrence of VLC streaming the second chosen channel.
3) I used an app for iOs, similar to VU+Player HD, and it opened the 3rd (transcoded) stream.
4) I then opened another session of VLC by OsX Terminal and I was able to open a .m3u file produced by tuner server and stored in my computer.
5) I opened a 5th session of VLC by Terminal as in step 4 (another transcoded stream).
Then I stopped but I don't see why I might not go on...
So, I'm playing 5 streams in different ways, 5 by VLC in my computer, another one by the iOs app, all of them transcoded. Should I conclude it's not a matter related to the Ultimo4K only? I'll let you to take your conclusions, as I don't need so many streams.

Notice that I have an SCR LNB, a Universal LNB (and three other terrestrial tuner, but they were not involved in this try).
I had not the chance to check for the used tuners by the GUI because I'm under the blanket with a terrible flu, at the moment!