After a few days with the MK3, some upgrades and firmware updates the dac sounds amazing, even without proper burn in.
Be warned It is very big, almost as big as my Hegel H300 amplifier so plan for it.
THE CAPACITORS
I replaced the stock capacitors with ClarityCap CSA 3.3 uF. Despite the huge difference in diameter size
38mm vs
20mm they fitted just fine. This is the first time i install caps so the result might not be so elegant but it works
I already liked the previous ESA caps but those are a nice upgrade. Mundorf caps are not my cup of tea, perhaps one day i will try the Jupiter copper caps but for now i am good.
THE TUBES
I replaced the stock tubes with EH 6H30Pi. It is my first exposure to these tubes as i never tried them in the past. My first impressions are positive they sound clean and extended but they luck some of the stock tube's liquidity.
IMHO the stock tubes are excellent and if funds are limited capacitor and rectifier upgrades should be a priority. I also use tube dampers and Pearl Tube Coolers that i had available since the tubes are big enough to accommodate both.
Despite having plenty NOS tubes, between the 6H30Pi and the stock tubes i got everything i need so i don't plan go crazy trying everything i have in my collection.
THE RECTIFIER
It was a pain to remove the stock rectifier. At some point i was scared the PCB will be damaged, i don't remember ever before a tube that was such a tight fit.
My first try was an RCA 5T4 that worked well but i heard a buzz sound from the dac so i removed it. I am not sure if it was a bad tube but i didn't bother to try any of the other 5T4 that i have.
Then i moved to a Mullard GZ34 and it was amazing but to be honest i have no intention to use such an expensive tube. It was mostly curiosity and yes they are as good as people say they are. Finally i settled for a new production TungSol 5AR4 and would like to try the WE Replica when funds permit. I do wonder if WE Replica fits through the opening considering the coke bottle shape.
THE FIRMWARE UPDATES
I flashed 2 firmware since i got the dac, they solved a few problems and now the dac works better. If you just got the dac i strongly recommend the latest firmware. I couldn't make the Utility that flashes the firmware work with Windows 10 but luckily i had an older laptop with Windows 7 and that did the trick. That been said, i had noise problems with Coaxial. I switched to USB so no big deal but if you plan to use this dac with Coaxial only be advised. This dac is heavily optimized for USB audio.
I noticed 2 fuses inside, one next to the rectifier and one behind the power button. I am considering a fuse upgrade, if you know the value and type please share.