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APS audio transformers

Custom audio transformers

We are no longer offering completed Signature Series or Signature Series PLUS DAC's however we can assist in obtaining a stock unit so we can perform the upgrades for you. We are only upgrading customer units at this time.  You send in your unit to be upgraded.

Signature Series PLUS For VIP Customers

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This sale inludes our Signature Series DAC upgrade with our R-core internal power supply installed.

This is the best sounding DAC we currently offer.



* SPECIAL For customers who had their unit upgraded in the past 6 months.*  $1499

Leave a note in the comments field at checkout stating your original purchase date.


* We may consider older perchases also... Just ask.


1) Transformer replacement. Replaced the Edcor 150 150 cheap transformers with premium R2 Nickel APS Audio R2 Transformers designed to meet extreme audiophile requirements. These transformers also brings up the gain to standard levels.
2) VOCM upgrade. The VOCM of these units did not have a low enough impedance for the video opamps used. We corrected this for the Signature Series by adding very high quality SMD poly caps (not the standard Vocm caps used on non-Signature Series) on each opamp power circuit which lowered the impedance the correct amount.
We also replace all 1% thick film resistors with 0.01% thin film resistors as part of our signature series upgrade.
3) RF.EMI shielding was added where needed This lowers any noise from entering critical circuits.
4) Performed DC offset tune. Lowers low frequency distortion and increases dynamics. This works together with our new R2 transformers.
5) In the stock power supply we tighten re-attach Power Transformer (All come loose at the base)  We replace the rectifier diodes with ultra-fast recovery diodes and seporate the 5v regulators to alow the digital input board it's own power clean low noise regulated source.


We take a stock MK1 and compleatly refurbish it with our new Rev 2 transformers, RF shielding, Power Supply upgrades including Tighten re-attach Power Transformer (All come loose at the base)
and tune the DC offset. 

What you get is an incredable sounding DAC that outperforms even the newest MK2 DAC even with our nickel transformers installed.  The Signature Series can be idenified by the new APS Audio Badging on the front.

This is a Level 2 upgrade.

Normaly $3995


This PLUS series addition is a Level 3 upgrade. This is the very best and most expensive however we feel it's worth every penny.


It includes everything in the Signature Series PLUS a super high quality internal linear power supply for the analog board.  It includes isolating filters from the digital supply.  This upgrade ads even more fine detail and increased REAL factor.  Percussive instruments sound so real and dynamic.


We have been working on finding the very best supply for this application and we feel we nailed it.

We use the complete bottom of the DAC for the heat sink keeping the internal temperature low. We use only the best capacitors and diodes available as well as using a high quality discrete circuit with a MOSFET (attached to the bottom of the unit) to regulate the voltage. The R-core transformer is icing on the cake and is very low noise especially with the thick copper flux band.

Signature Series $3995 + PLUS $829 = Total $4824 Normaly $4394 for our Signature Series PLUS (Level 3) The very best!


VIP Customers gets all this upgrade to their unit for just $1499

About Us

We have been designing and building custom upgrades for the directstream DAC since 2019


You can read some reviews and find out some more info about our products here and here



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We are located in the

Baltimore / Washington area