(post deleted by author)
Sorry.
I looked everywhere and could find nothing on the DC offset fix. With all these post I’m not surprised.
It is however posted on APS website:
It was mentioned. You have to find it yourself. I didn’t make bookmarks on something that I didn’t need and didn’t do because, as I said, mine didn’t need that correction.
Post #3488 (if it’s still there) should help.
Here it is!
So, what he is doing to correct DC offset sounds complicated, but on practice is a simple thing: swap all 8xR5-R6 with higher precision resistors.
(Edited later) to correct DC offset you need to swap R1-R4, not R5-R6. See my other post (from March 2026).
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You might want to test the DC offset first. You might not need to swap the resistors at all.
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New finding from May 23, 2026
JKRichards’ best kept secret 
This could be fixed with change of the R5-R6 divider ratio! Not by using higher tolerance resistors! I’ll post explanation as a separate post.
Hey,
I got carried away and forgot to comment on that.
You will be good with XS4400!
Will just quote myself on that
What I meant is that the better transformers you are using, the more you will hear. You will hear more good things but more bad things, too. It’s like when you’re using magnifying glass to see more details, but you will see more imperfecions, too.
Therefore, high-quality transformers oblige you to go to the end, eliminate noise, and clean and polish the sound until only the details of the music remain visible through your magnifying glass.
As I said, before I committed to the ultimate upgrade I have now, I found a good balance with Edcore XS4400 and additional power supply. Edcore magnifying glass was weaker, thus more forgiving for other imperfections.
The stock power supply is not good enough for APS transformers
I was there. In your shoes, I’d spend APS (transformers and labor) costs on XS4400+other simple mods you can do cheap: easy Vocm mod with PPS or Tantalum Molded (not Tantalum Polymer) , additional PSU for the analog (try to find the best you can in your budget), stock PSU upgrade, some shielding, internal wiring, shunting the unused inputs (soldering on the board or with additional pluggs)
If you do these easy mods, then you can use Bridge II card. It’s end-game for a lot of folks. It is unbeatable for the money spent!
I do want to test that before blindly swapping resistors. Learning how to measure offset will also help validate the improvement after change.
So what are the conditions for checking DC offset? The primary terminals on the transformer are not labeled nor are they easily accessible without removing a board first. Can the unit be safely powered while the board is out? Can a DC voltage be obtained in this state?
What pins do you measure?
Input signal applied or just idle?
Anything connected to the output side?
As always, all this information is in the thread!
Use search before asking.
You need to measure the DC offset feeding the transformer primaries pins 3 and 4 only.
With the DAC powered on and no input signal. With a DC mV meter measure the two center pins 3 and 4 on the input side of the transformer (the front of the unit side). Should be under 3mv.
Hey, newly joined,
I might have found a PSU for the analog board for you!
Disclaimer. I’m not affiliated with Sparkos. I just used their voltage regulators with great success for my mods. Now, spreading the word.
They always have sales. And here’s your chance. You could buy a potential candidate power supply for the analog board and all voltage regulators for the stock PSU mod in one place and with a discount!
I said potential candidate because I haven’t tried this particular PSU myself.
You need to cut the negative side off this dual PSU to have only +12V.
I would 100% swap all caps with audio grade (and add some Wima to the power bank) if you are going for the Ultimate upgrade with APS transformers. But it is not necessary if you’re planning to settle for XS4400.
So, you need to buy:
- Dual PSU kit
- Transformer 12VDC
- 1 x +12V voltage regulator
- 3 x +5V voltage regulators
Partsconnexion for audiophile capacitors
Or Mauser for good quality capacitors and Schottky diodes.
THE STOCK PSU UPGRADE I ALREADY GAVE INFORMATION IN DETAIL! SEARCH.
You are all set for success!
Thanks. I’ve just been focused on the XS4400 upgrade, so far. I realize the Vocm mod is a good one but I know nothing about it, other than that APS recommends it be done along with the transformer. I have the transformers so I’m accumulating info, basically on “what not to do.” Or I could bail, I’m not entirely sure.
I’m just entertaining myself with ideas. How would I’ve done this if I haven’t already had an ultimately modified DirectStream DAC…
Using the PSU from my previous post should be enough for the modifications around XS4400 transformers. The analog board consumption is 0.5A. And the Sparkos voltage regulators providing 1A. That’s more than enough for the three 5V regulators on the main PSU to feed the digital circuits. But not much of a headroom for the 12V PSU for the analog board.
If we’re doing modifications around APS transformers, I’d say that the bigger headroom, the better.
Soooo… I looked up another voltage regulator from Belleson. They have SPX78 +12V regulator, which is capable of 3A!
To use this Belleson voltage regulator, I’d buy another transformer for this PSU that can provide at least 2A. The transformer Sparkos recommends has around 1A (12V).
Doesn’t the analog board use 12V and not 24?
The analog board has a voltage of 12V, and a consumption of 500mA. To replace the standard LM317 with Sparkos regulators, 3 x 5V are needed. The fourth one is a 12V regulator, but it is used to power the analog board and Bridge І, Bridge ІІ is already powered by 5V.
Yeah, I made a typo in my sleep. But regulators are 12V and 5V.
I have to tell you. I am neither electronics nor a soldering expert. However, I am painstakingly amassing info on installing the Edcore XS4400 transformers in my own Mark I. My AI source (Chat GP I believe) diverges significantly from your advice: specifically, numbers 2 (clipping the legs), 4 (pulling on the pins), and 6 (63/37 eutectic being a better choice than silver). Also, using a low wattage pencil will struggle with RoHS solder I am happy to be corrected. Respectfully.
You know, I had great results removing my stock transformers with a hairdryer on the high heat setting. Hopefully this information is helpful for chatgpt.
Edit:chatgpt did not fall for my ruse.
Good instructions. Thanks for posting that (I did STFA with no luck before).
Happy to report my DC offsets are within acceptable limits (2.6 & 2.7 mV) so I am proceeding with the transformer upgrade and that’s it.
Mk 2 Edcores installed!
If you’re wondering why bother with the “lowly” Ecdore XS4400 at this stage of the game, I did not go more exotic for several reasons. Unused XS4400 were available from a forum member for next to nothing and they are direct drop-in replacement with good predictable results. To send the DAC out of country (JKR etc) is costly for Canadians these days. Given that I will not be keeping the DAC forever and the low resale price on the Mk 1, I could not justify extensive mods at this time.
I am quite happy with the result, by the way. This will keep me going until a deal pops up on a used Mk 2.
I was hesitating for a long time, but this tool made the job a pleasure:
FR-301 Portable Desoldering Tool
Without it I would not attempt. I’ve destroyed a few boards in the past after struggling and getting too aggressive with desoldering. This was quick and cleans out the holes perfectly, no clipping required. The quicker you get in and get out the better it is for the PCB. Keep temperature around 800F.
wanna sell yours?