Managed to squeeze in a bit more A/B with the R8 (Turbo mode) & Sp2k for Traillii, sharing quick impressions below:
Bass: Although Sp2k has a more neutral bass, it has the better bass presentation mainly because R8's midbass seems to actually accentuate the Traillii BA timbre a bit on certain recordings. Subbass rumble is quite similar, but there is more organic heft to the Sp2k impact, so clear winner there. R8 does have a bit more color/warmth, but not enough to offset the timbre discrepancy.
Mids: Although soundstage depth is better on SP2k, the mids are pushed back more mainly because of how
tight the entire signature is off Sp2k. This tightness to the transients allows the notes to breath and image on the axis easier than the R8. R8 does win in terms of mid engagement, however-mainly because the sound is a bit more forward and the
upper mids are fun as hell. Female vocals are sublime, albeit a bit colored and exaggerated on the height axis. R8 does also do violins and other stringed-instruments better in terms of musicality, with more color and low-level detail. I feel I can actually feel each string plucked with that emphasized upper-mid range.
Treble:Sp2k has the best treble of any DAP I've heard. And what happens when I pair it with the best IEM treble I've heard to date?
. Sp2k treble is clearer, with more space and bite. R8 does have more color and actual sparkle, which can be fun for those not looking to analyze as much.
Verdict: There is space for both in one's collection. R8 is the more musical DAP if midbass for BAs is not an issue, but it is pretty obvious that Sp2k is the mature, refined signature in comparison. For Traillii, go for:
-R8 if you prefer upper mids and emphasized instrument timbre
-Sp2k if you prefer maximizing technicalities with incredible treble, weighty but neutral bass, and organic, spacious mids.