Yes, JDS' ODAC with RCA jacks comes in the bigger case.
The O2 was designed (at least in part) to be a simple, inexpensive project for electronic hobbyists. One of the trade-offs between functionality and price is the lack of room on the O2's circuit board for a 1/4" jack. The O2's designer discusses this on his blog along with instructions for the mods needed for the bigger jack. But, linking to it from this forum is against the rules.
Thank You very much for Your explanations. So, the O2 design does not 'prohibit' the 1/4" circuitry.
I'm sure that the 1/4" jack does not 'outstretch' the O2 capabilities and does not affect negatively the sound quality of the O2.
I'm not a DIY'er nor and an engineer so I don't understand the (highly) technical stuff
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