Absolute top tier DAC for standard res Redbook CD

Klh007,
This is my own mod after open the dac up and figure put why factory version has compressed and slow high frequency response. Oppo used cheap diodes and capacitors in a 800 dollar retail price dac which is understandable.  I introduced fast diodes and 6800p silver mica bypass caps in power supply which make sound much smooth and faster.  I want to remove all those unnecessary coupling caps w/ shunt circuit and replace rca plugs with telflon ones which require majr surgery. For now, just bypass cheap couling cap w/ cooper coil and teflon caps, resulting fast and coherent sound for my violin concerto cd and dff collections. Total cost so far including above components and teflon post, crazy glue and teflon 22ga wires is about $250. Of course labor and research is free for myself.

It's easy to see why Dan Wright has chosen to mod w/tubes both the OPPO 205 and Sonica, great foundation for advancements. You might want to start a thread detailing your mods and experience with the Sonica.

Klh007,
Thanks for your suggetion.i will try transformer based mod for sonica dac,
Replace iv and buffer ic circuit with high quality microphone transformers.
Tube mod in such a small package is very challenge. I built all my tube preamps and power amps, the key for a good pre amp is regulated /shunt power supply, which take a lot of space.

Btw, the hidden gem of redbook cd dac is old bbrown 1074 dac chip based assemblage dac. I have one heavily mod w blackgate/silver mica and opa637s. Chinese audiophile writer mr chen had high praise for it(w/o my mod version).

Dlcockrum,
Humm,cnn.  Who‘s owner of cnn? He dumped his chinese wife right? You think i agree anything nonsense little  Cumo makes on cnn?

Regarding mod, as mr chen claimed, only good judgement should be based on golden ears,if and only if, no other way. Money is not, approach is not (tube vs solid state), feature is not even a fact for audiophilers. I perfect ok that none of my amps and lp turntables have remote control. So, why some device makes bettet sound? In dac case, in dgital domain, once power is clean, clock is acurate, data stream just feed the same dac chip w/o any difference (nowadays, chip makers reduced to very few anyway).
So the answer is how analog signal get filtered and amplified from dac chip analog output pins.cheap approach is ic based low quality circuit used in tv and computers, those design should not used in high end audio. But selling audio equipment is a buisiness, cnn like media feed all kinds of crab to confuse consumers. Use your ears, not looking at price tag to decide which one is better.

As oppo dac goes, it is my attempt to play both cd and dsd lp achieving files with a mobil phone app. I actually would be happy if it is half good as my assemblage. Now it exceeds my expectation:it has latest dac chip, it uses one of my fav voltage amp ic 4562, its usb interface is decent.i just fixed the weak spots of power supply and coupling crab(good preamp should never use capacitor coupling unless western electric ultrapath design for tube amp).
Btw, my korg dsd recording has same issues and more(bad ic chips in signal path), so i have some experience to deal with unnecessary coupling. In korg case, i just short the caps. My phono stage line out is transformer coupled, no reason why recorder needs coupling caps in front.