Computer is noisy
It is very well known that computer is noisy, both literally and electrically. Many have attempted to clean up the power line using various caps, regulators and isolation. However, the noise is not restricted to the power lines. The Ground is also involved. Even if you can filter out all the noisy powerlines, there are still many switchers on the mother board that you can never eliminate.
After a lot of research, I come across a company located in Canada. This company produce a PCI-e extension solution over optical cable. This is not toslink type of optical cable, but those used in telecommunications. The max transmission speed is 5GT/s and is sufficient to support my 8 channels convolver setup.
But the most important thing for us audiophile is that, using optical cable, there is absolute galvanic isolation between the host computer and the sound card. And I can of course use the best linear power supply for the sound card.
Here is the implementation. As you can see the picture above, the main board only requires +3.3V which is provided by Belleson PSU. The board comes in as default using ATX power supply so you need to change the jumper J9 to pin1-2 and the DIP switch 1.4 to ON. This arrangement allows you to start the module without logic circuit which is common with ATX power supply.
My RME HDSPe AES requires +3.3V amd +12V. Current requirements are 400mA 4.8W (12 V), 760mA 2.5W (3.3V) = 7,3W Total. I order the connection cable from here
Cut the trace for +3.3V, +12V, all Grounds and reconnected those up with linear power supply from Belleson.
Stunning! The sound coming from my system is now very organic with a very dark background. The transparent, the separation among each instruments are so clear. Now the noisy computer is no longer part of the problem!
With AOIP, isolation can be done in a whole new different level. AOIP allows all connection back to Level 3 switch. Instead of RJ45 LAN port, one can use optical connection for complete galvanic isolation. All my computer based hardware can make use of Optical connection but Merging hardware is not ready yet. So I decided to use Cisco switch that comes with 2 optical port. I can then use optical - RJ45 converter for connection with Hapi. So all the noise from my computer hardware are not transmitted to my DAC.