Hello Yoshi,

I think this is a tricky question to answer.

1st, I don't think this is a Decware amp. At least it is not like Decware Taboo MKIIIs I know of. And it does not look like Steve's aesthetic style either, so I am guessing not some prototype either....I suppose it is possible it could be someone's attempt to copy one, but it is different in layout, connectors, transformer appearance, wooden base......

A little complicated, in that we don't know how the amp is made, or if something got messed up in shipping. There could be internal issues contributing to  noise. Also a buzz/hum can come from defective or noisy tubes, ground loops, possibly your sound card (?), computer EMF/RF interference due to being too close to the computer electronics and wifi, computer noise getting into unshielded interconnects.....and more. You can get amp hum from a noisy AC outlet/circuit...or from DC offset...lots of possible causes.

The big tube looks like it could be a RCA 5U4GB and many have 5 pins, many other 5U4Gs having 4 for an 8 pin socket, so not necessarily a worry there. If it is a good tube, and a 5U4G, it should be fine with a Taboo layout (if all else is like the Taboo design electronically). Rectifiers and input tubes in particular can be noisy and still work fine though.

Bringing up the question, how noisy is it?

Have you used this computer, sound card and cables for other amps without noise?

Is it in both channels?

Does it change if you move the amp further from your computer?

Do you have different interconnects you can try to see if that might be the problem?

If it were a Taboo, and you can't solve it with forum help, you could call Steve as a last resort, but I can't really come up with reasons to imagine that it is a Decware amp...If I am wrong, I hope someone will clarify that! But if i am right, and it was billed as a Decware Taboo MKIII, that would be pretty suspect, casting questions on the character of the seller and quality.

https://www.youtube.com/watch?v=3REav2esmZU

https://www.youtube.com/watch?v=5TPO0FDAoaU

I dont hear any noise when my headphones are plugged in to the amp, but i disconnect the RCA cables.

I tried another amplifier an old Technics and no static noise, with the same cables.

When i plug in my headphones in to my soundcard and i enable SVN (whatever that is) there is also some noise coming.

I highly doubt that someone tried to remake Steve's amp, the black surface is the same, the headphone jacks seem the same too.

Also these golden things you can unscrew are the same.

I have never heard this sort of sound with audio, but like Donnie suggests, it sounds like it could be some weird computer interference to me too.

"I don't hear any noise when my headphones are plugged in to the amp, but i disconnect the RCA cables."

If the amp is on, in this same proximity to the computer as before, and turned up, this seems to indicate it is not the amp, leaving interconnect cables, or sound card.

"I tried another amplifier an old Technics and no static noise, with the same cables."

That I don't understand.

"When i plug in my headphones in to my soundcard and i enable SVN (whatever that is) there is also some noise coming."

Is this with both amps?

Was the Technics set up exactly like the new amp was, proximity to the computer, IC cables, power cable, all settings the same....

"I highly doubt that someone tried to remake Steve's amp, the black surface is the same, the headphone jacks seem the same too."

"Also these golden things you can unscrew are the same."

That the amp plate is the same color and similar texture, or that the same looking headphone jacks were used, does not mean a whole lot. If you look and compare very carefully - at the size proportions, screw placement, tube placement distances, the binding posts used (those golden things you can turn for speaker hookup), the transformers used, the way the base in made and shaped, these are are all different from Steve's standard makes....not like Steve's typical design for this platform. This is definitely not a stock built Taboo MKIII, the last model. As far as I can recall, typically, when Steve makes amp changes, it seems he uses the same, or similar platform he has been using for an amp, and when he makes new setups, there is a style that is recognizable. Though I suppose possible, this just does not look like his style to me. My guess is that these are all signs Steve did not build it.

This does not necessarily mean the amp does not have good audio potential, just not likely Decware by my best guess.

Lon was right, i contacted the guy that sold me the amp and it turns out it's not an original Taboo MKIII, it has been built based on the original drawings and parts list (that's what he told me).

I followed Donnie's advice and plugged in my Galaxy S7 phone, with an RCA to 3.5mm adapter cable.

There was no noise, except when i paused a song or closed the music app there was some noise present that would disappear after 3 seconds ca.

There was no static noise when using another amp or my soundcard directly, only with SVN enabeld.

Well i thank you all for the support. I will order an external DAC.

Small update on this issue.

I ordered the DAC and the issue stayed. It turned that the problem is a ground loop, this can happen when there are multiple grounds from different devices, i dont know the exact technical explanation, but somehow when there are multiple grounds they start to interfere with each other and then that noise gets transmitted through USB.

To solve that problem i will need to buy a USB isolator with galvanic iisolation. Most of them are specifically made to break ground loops and clean the usb signal.

A balanced connection would also solve that problem, but my amp doesnt have balanced inputs.

Best regards