If you mean the B.L.U.E. Yeti, that is intended for desktop recording (that is, not portable). If your DSLR has good audio already, then perhaps invest in a good shoe-mount and shotgun mic for mounting on top of the camera, like this:
http://i.ebayimg.com/t/Stereo-Video-Shotgun-Mic-Canon-EOS-60D-/00/$(KGrHqEOKicE31fQ1Fl9BN-2WJ7QQ!~~0_3.JPG
Otherwise the H4N grabs good audio for instruments and voice, but now you’re talking a whole separate system. If you are shooting video and synch audio with two systems (two devices, as in video on the DSLR plus audio only with the. H4N), then you would be creating more work for yourself in the end. But if you don’t need the video from the DSLR, then the H4N actually shoots decent video and really good audio (Xoom are known for their good sounding audio devices). You could also check out Tascam, or even Olympus for a “consumer level” recorder that’s pretty decent.