Per Lindhof wrote:...
What I do is the following:
I make a nice recording in my studio.
Burn it to a CD
Play it on my Hi-fi - it sounds nice.
Upload it to for example Soundcloudor Youtube
Play it on the same Hi-fi via the computer/Soundcloud - it sounds boxy and thin..
If I play it on the CD drive on my laptop the same poor result happens.
Where in the chain does it go wrong?
Let's look at this more carefully. If we want to know what's causing an effect, we need to be taking account of one thing at a time, and it seems that there are steps being jumped here.
But firstly, never even think about assessing audio critically over laptop speakers. Ever.
As already observed, there is the question of the conversion back to analogue when you play the audio back. So eliminate all the possible other causes of the problem I suggest;
i. Take an existing recording you find high quality over your hifi
ii. convert to best-quality mp3 yourself (optional but preferable)
iii. upload (the mp3) to YT and Soundcloud
iv. download the exact same track from YT and Soundcloud
v. burn the original mp3, and the two downloaded versions to CD and play over your hifi. Make a note of which is which track!!!
The point about re-downloading what was uploaded rather than streaming it is that your computer is no longer involved in the conversion from digital back to analogue. Few if any computers let alone laptops have soundcards that would ever come close to a decent hifi in handling audio.
I suspect we also need to more about your studio; what is the gear, how is it organised, are you able to play an internet connection back via the same gear? And do you have decent studio (not hifi) speakers to assess your sound before it goes to the hifi? The latter will tend to be kind to your sound and not 'honest'.