I have the C5D right not and I personally feel that it's not up to snuff. It sound artificial.
The thing is I've tried feeding other DACs to the O2, and I could notice the suttle differences, and favor the ODAC. The thing is I need a good DAC/Amp combo, and from what it sounds, you think it's the amp that makes the sound transparent. I put lots of weight on the ODAC also. Without both, it's not transparent to me. I guess I will try the Leckerton and find out if it can match the ODAC/O2 combo.
I will get an ODAC in the future and make further comparison. My DX50 with Rockbox sounds the most transparent to me.
I agree the C5D sounds artificial. I was hoping it to be closer to O2 since JDS Labs is making both O2 and ODAC. It would have been the perfect portable amp since it's thinner and narrower albeit longer than the leckerton but matches most DAPs in dimension.
It actually stacks perfectly with DX50 and is friendly inside my pocket. (loose pocket, not the tight ones :) )