Having owned both, I believe the HifimeDIY is on par or better than the ODAC. I will likely get the HifimeDIY in the very near future because the ODAC offered nothing over it for me. (For your information, I have listened to all these headphones to date, many of them with my signature's listed equipment:)
Warning: Spoiler! (Click to show)
I have extensively demoed (or owned, in bold) the following headphones:
AKG K812, K712, K702, K701, Q701, K550, K271, K240 Studio, K77; Audio Technica ATH-M50X, ATH-M50, ATH-M40X, ATH-M40fs; Beats by Dr. Dre Executive, Pro, Solo HD, Studio; Beyerdynamic T5 P, DT 990 Premium 600 ohm, DT 990 Pro, DT 880 Premium 250 ohm, DT 880 Pro, DT 860, DT 770 Pro-80; Bose Quietcomfort 15, Quietcomfort 3, Quietcomfort 2, AE2; Creative EPH-630; Denon AH-D7100, AH-D600, AH-D340; Etymotic ER-6; Grado PS500, Grado GS1000, RS1i, RS 1, RS 2i, RS 2, SR325is, SR325i, SR225i, SR225, SR125i, SR125, SR80i, SR80, SR60i, SR60, iGrado; The House of Marley Redemption Song; Koss Porta Pro, KSC75, The Plug, UR10; Phonak PFE (with gray filters); Sennheiser HD 800, HD 650, HD 600, HD 598, HD 595, HD 558, HD 555 (also modified to HD595), HD 380, HD 280, HD202, HD201, PX 100, Momentum On-Ear, Momentum Over-the-Ear; Shure SRH1540, SRH940, SRH840, SRH440, SE835, SE535; Skullcandy Aviators, Crusher, Hesh; Sony MDR-X05, MDR-XB500, MDR-7506, MDR-V6, MDR-55, MDR-CD30 (I almost forgot about these; purchased at a garage sale about 10 years ago); Superlux HD681, HD688B; Ultimate Ears TripleFi 10 (family member owns them); Ultrasone HFI-780; Westone UM Pro 30, UM Pro 20, UM Pro 10.
The HifimeDIY has better crosstalk performance and, given its inferior testing equipment compared to the ODAC's testing equipment, it has likely equal or better distortion, noise and dynamic range performance.
Edited by Hifihedgehog - 2/9/15 at 12:34pm