"I will say this. When my hiss was audible to seating (to me) on certain passages played on certain sources" - (or another suggested fininsh to your sentence if you dont mind), its because its in the source.
This is exactly true and I have been concerned that many listeners digging for hiss might confuse these two. The Outlaw is very revealing, If you have never heard that amount of detail from your current system, it takes some getting used to. When I was messing around with ‘hiss’, I did make that mistake, believing I was hearing noise interjected when traced in reality turned out to be in the source/recording itself.

Other than speaker trim, calibration and crossover setting what other things can be done to help liven up the DTS modes?
I’ll think - and try to pay attention if/when I have time to optimize the Viennas this weekend; what changes I make this time. Something you might try is playing with the treble/bass trim in setup for your speakers. Find a scene/recording that appears lacking and loop while changing these. For my setup this directly correlated to reducing some of the ‘flat’ I heard. My Def Tech needed to be set at (I think +2 on treble) The Vienna Beethoven’s preferred 0 but I have not spent time truly optimizing yet. The jump was such (another) leap forward with the new speakers I’ve just been ‘enjoying’. My time to play in settings does not always coincide with when I’m not working. When the phones let up, (evenings/weekends when I send to voice mail) then the A/V tends to be always in use and they get touchy about me interrupting! The other night the center came a night after the fronts my husband placed it then I pulled out my sound meter and they all yelled NO. (They were watching a movie).

I really did NOT have my new plethora of sound modes down the first weeks. I would hit a particular one that sounded good twice in a row and stick to it. (Not a good idea) With time and familiarity I learned which would optimize best for each source and the quality of the individual recording (regardless of source). Across the board properly implementing these - everything is stellar. But then I made some pretty funny mistakes (ask Matthew) like the time I commented to him here in the forum about trying some Cirrus modes and how they affected my sound. (I was even using one as my version of a ‘night compression’ mode- hey - it did what I wanted compressed some peaks) Matthew had to tell me I had speakers set incorrectly for 6.1 (I was running 5.1). I was not ‘wrong’ in the sense that they did/could affect the sound. Try setting your system for 6.1 or 7.1 if you in actuality have 5.1 set up you will hear some differences on these modes depending on source.
It WILL steer the sound differently.....there was just that tiny matter of no sound radiating from that non-hung 6th speaker I had going on!!!

Play and play more that’s what I recommend.