Bass response from the C3 with the TF10's (fitted with a Dark Lord cable) is a little light for my tastes compared with the Zip, which is a little heavier. That said, the TF10's are as crisp as could be with the C3, with kick drums coming through with punch, but sub-bass and mid-bass not as deep and well extended as the Zip. My feeling is that if you are looking for bass clarity then you'll be fine buying the C3 and using it with TF10's, but if you are looking for bass depth, then given the C3 has no EQ, you might want to look elsewhere.
Comparison for bass with the Zip was carried out using the album 'My Way' from Skazi, in FLAC format, ripped from CD with dbPoweramp and AccurateRip. This album has complex and deep synthesized basslines and sub-bass patterns, and kick drums that sound like they are pounding the bridge of your nose from inside of your head when used with the right setup :-) No amps were used for this particular comparison with the Zip, and no EQ settings were setup on the Zip.
I wouldn't want to say anything more at the moment as these are impressions only, and I need to take some extended listening time with different styles of music and bitrates. I am only responding at this time, to give you an initial impression of the bass only, for particularly bass heavy music.
EDIT: For the purposes of clarity, there are some pre-defined EQ settings available on the C3, when I say that there is no EQ. Presets don't count as EQ as far as I am concerned, if they are not at least adjustable in some way :-)
Edited by phlashbios - 9/14/12 at 8:49am