Thanks for suggestions, Steve. If I get a better DAC, I guess I still need to worry about transport, e.g., metrum octave seems only show its potential with a reclocker. Also many discussion about USB to SPDIF converter, and those DACs that has asynchronous USB often has better performance on optical/coax as opposed to the USB, which is hard to understand as I thought asynchronous USB address the jitter issues with source and DAC in separate box. All these makes feel that maybe I should wait a bit on these new DACs.
Of course I don't mind trying these new DACs but here in Canada the only way to do that is to buy it new or used and try.