Thank for your answer, but what I mean is, It sounds the same to me as my CD player alone.
Usb from the laptop sounds different than both with the same file/song.
I think I can answer this - and the maybe clear up a few things.
The DC-1 is quite
NEUTRAL.... which means that, overall, it doesn't have a glaringly "distinctive" sound.... it simply lets you hear whatever's there in your recording.
When "audiophiles" discuss DACs, it can be a bit confusing to non-audiophiles, because audiophiles fall into two broad groups....
One group wants their equipment to be as accurate as possible. (In general, studios fall into this group - at least with DACs - because they want a DAC to let them hear exactly what's there - no more and no less.) This is how we designed the DC-1; to be as accurate as possible; and we think we succeeded pretty well.
However, to answer your question, even a halfway decent CD player is pretty good (reasonable S/N ratio, reasonably flat, reasonably low THD), so going from that to an even more accurate device is going to be an incremental improvement, and how much you gain by it is going to depend on your source, and your other associated equipment, and isn't going to be "earth shatteringly dramatic". (Think of it like buying a three-foot ruler. You want a ruler to be as straight as possible, and you want the markings on it to be as accurate as possible. However, even a $5 ruler is actually pretty straight and the markings are pretty close to where they should be. Now, you can spend $100 on a "high quality machinist's ruler" and it will be even more perfectly straight, and the markings on it will be even more accurate, but, since even the cheap plastic ruler was accurate to within 1/8", even a $1 million LASER interferometer can't improve on it by more than that.) On good quality content, and with good associated equipment, the DC-1 will sound better than even most expensive "all-in-one" CD players, and that difference will be in the direction of letting you hear more or what's there, and making sure you're hearing it exactly as it's recorded, but the difference will be subtle.
Of course, in a studio environment, like in a machinist's shop, part of what you pay for is assurance. You want a DAC that's good enough that, whether what you're listening to sounds great or not, you can be sure that you're hearing it exactly as it really is.
Incidentally, that other group of audiophiles is the ones who simply believe that their equipment should make their music sound the way they prefer it - and consider accuracy to be secondary. (This is slightly different than "subjectivists" - whose goal may or may not be accuracy, but who consider what they hear to be more important than measurements). There are a lot of DACs out there which are designed to satisfy this group; DACs which have very distinct "sound signatures", and all sorts of interesting colorations, and some of which sound very different than others. (When there is one single objective "correct", everything that approaches it tends to sound more or less the same, and the differences exist solely in the details; when you don't care about accuracy, you have a lot more room for variation, and things can sound very different. Also, as long as your goal isn't absolute accuracy, then there's no right or wrong; whatever you like is "right".)
As I mentioned, the DC-1 was designed to be accurate.... which is what we think is right for a piece of studio playback and monitoring equipment.
Assuming the CD player is playing the bits without altering them, and your computer isn't configured to alter the signal somehow, and assuming the content itself is the same, there shouldn't be a major difference between USB and CD playback - which makes me wonder what's going on there. (You do want the DC-1 set to "asynchronous" to remove any jitter from the CD player when comparing the two.)
