Hi Ungaro. Let me preface by saying I am well aware the following observations fail miserably due to many flaws in methodology! With that recognised, here we go....
I played the Weekend and Three 6 Mafia tracks using Spotify's highest quality audio setting on my iPhone 6S Plus. I listened through Shure 846s with LTG cable and Sennheiser Momentum 2.0s using the 3.5mm audio jack. Hopefully it is no surprise that the Shure's outperformed the Sennheisrer's in most respects.
I first listened to the tracks with the Shure's. Although unfamiliar with the songs, given the genre, I sensed that there was something missing from the bass. Listening to the same songs through the Momentum's and then again through the Shure's, my opinion changed somewhat. The bass seemed stronger than before. But I can't put my finger on it, something still didn't seem right.
Listening to some tracks that I am more familiar with including Adagio for Strings and Traffic (Tiësto), Love You More and Zacalo (Armin van Buuren), Bratzke (Super Flu), Dancing on My Own (Robyn), Teardrop (Massive Attack), Mo Boy (Dillard), Why So Serious (Hans Zimmerman), and Nothing Matters (Mark Knight) my opinion was the same as when I first listened to Six Feet Under. There definitely seemed to be an attenuation of the bass compared to the original 846 cable. The initial impact of bass seemed softer on all the familiar tracks. Yet, the sub-bass on Why So Serious at 3.26 was outstandingly deep and could be felt to a greater extent than using the 846s original cable. Conversely, there seems less impact when the bass kicks in on Mo Boy.
While I cannot pin-point exactly what is happening with the bass on the 846/LTG combo, there is no question that the overall sound has a wider soundstage and greater detail than with the original cable. Here are my impressions:
1. Given the iPhone is a constant, at this point it is impossible for me to differentiate the effect of lack of sufficient burn-in of the 846s (if any) and the effect of the LTG (if any) on bass performance. My hope is that the bass will return with the strength that I remember from before.
2. If things simply are what they are Ungaro, the 846/LTG combo will not likely be favorable to you. There is definitely something lacking in the bass.
3. IMHO, the wider soundstage and finer detail is worth the slight loss in bass. What that "loss" is, I'm still not sure. Given your apparent favored music genre, my gut tells me bass performance will likely fall short of the 846/Onkyo combo you are currently using.
4. I know this is a very sensitive issue verging on blasphemy Ungaro, but have you considered, you know, eh, um, that B brand?
5. Only you can determine which combo will offer the sound you most enjoy. Keep us posted on what you decide.
Ciao.