After 10 days, here is my feedback on the Gustard X12 USB if you're interested
(and sorry for my english)
Disclaimer : I do have a K701 and a iFi ican but I listen music on speakers most of the time (Hypex 180hxr, B&W cm7, velodyne spl800 ultra).
Background
I have a hiface (first version) connected to a TC electronic BMC-2 dac. It's a well known dac in france and after many years I can say it's a rather good dac. Everything is connected to a dedicated computer on linux (Daphile) with large buffers and finely tuned Alsa settings. I was previously on OSX with Pure music.
Day 1
The USB is plug&play. it's a nice and heavy box. It's feel ready to stay powered on 24/7
Noticed great improvement regarding the matching with my passive pre-amp. The X12 really drive the whole chain flawlessly. Low volume listening is clearly better. Digital volume is also really good and helps a lot to find a perfect matching with the amp.
I had to lower the subwoofer settings to find the right balance
There's a lot of resolution. There's also a lot of energy, way too much energy...
Day 4
Sound is very detailed, no question about that. I hoped some burn-in will greatly smooth the sound but there's no improvement so far. I have also noticed that the Dac needs power from the USB (5v)
. A cheap USB lithium battery helps a lot and I finally got something good.
Day 6
I have tested the old hiface with spdif input and the same USB battery. Oh oh !
Yes, the first hiface is clearly better than the dac USB input. In less than 30 seconds of music you immediately notice the difference. To tell the truth at this point I'm not even mad because it sounds so much better. I found that the dac in itself is really, really good. I finally get the "upgrade" feeling and chills with the music. My setup never sounded like that and it starts to totally justify the 500€ I paid.
In the other end, I don't even know why Gustard engineers bothered to put an Xmos chip in the dac. It's dull and useless.
Today
Cheap USB battery can produce some RF noise despite low ripple and overall good performance. (most of the time, voltage is boosted to reach 5v). I had to test a very very clean 5v power supply to make my mind on the Gustard X12 USB input.
I have made a cheap Alcaline battery pack (4 AA cells), unregulated and slowly discharged to reach 5v
Yes, there's a catch
The dac USB input finally catch up with the hiface and even exceed it !
I wasn't expecting that but at this point the setup is so transparent you quickly notice the shift on the soundstage. It was deep, now it's deeper and clearer. No matter how hard I try to push the old hiface, I can't output something as good.
At this point, I don't know what to think.
I'm in a middle of my honeymoon with this dac and I may be wrong but I don't even think the U12 could add anything the sound.
Back to the thread
Those alcaline cells will be dead soon and I will come back to reality.
I will come back to questions like Regen or Wyrd or iUSB or Aqvox ? or question like do I really have to pay half the price of the dac to have something I can have with few AA cells
?
I have already made tons of optimisations on the computer side to help data transmission with overall good results (dedicated computer, playing from ram, etc). I wonder why there is no cheap commercial battery solution for USB power supply. I'm sure something can be made for less than $50.