Your existing setup is pretty nice. You probably won't hear a huge difference but it will be noticeable with critical listening. The CEntrance DAC has better instrument separation and a wider soundstage than the iPod. If EQ'ing is your thing (which it is to me) you'll like the bass and treble boost features. I also find that playing with the Impedance settings and taylor the sound a bit too, but it's subtle.
I think the M8 is well suited for jazz recordings as it has a nice midrange presentation. You will have to put the bass on Setting "2" in order to get those lush bass notes to come through. The M8 has good extension but is slightly lacking in low-end presence unless you utilize the bass boost. I do not find that the bass boost colors any of the sound outside of that frequency range, aside from a slight boost in overall gain.
Edit: You also have the option of ditching that horrible Cardas cable (just kidding ) for a balanced setup.
Edited by SoulSyde - 11/24/13 at 6:06am