Modding the PS Audio Directstream DAC MK1 and MK2

I didn't say there's no difference. There is. It's just my experience: power supply mod brought more changes than swapping 4400 with APS even WITH Vocm mod. 

The most of the things people described as APS transformers change in the sound: tight and beefy low end, melodic mids, and nimble highs - all these changes did my power supply mod after I installed the 4400 transformers. And APS transformers just tightened and cleaned up the same ALMOST perfect sound signature that I had with 4400 w/PSU before. Now, with APS transformers, it's perfect. 

Shame on me, I haven't done the Vocm mod before I swapped the 4400 with APS transformers... I  wish I could discern the Vcom mod impact on the sound. 

The internal power supply is fine in the unit as there are many up stream regulators and filters. It’s not necessary to use an external supply for this reason however using an external supply will remove some heat from inside the DAC.

Also that bridge card destroys the sound of the DS DAC. Best to remove them.

We are the ones who designed and built the APS transformers.  We did extensive testing with all configurations of the DS.  This is how we know what improves the sound and what doesn't.

I think your Bridge II card is flawing your listening. When we did testing, the Bridge card totally trashed the sound quality no matter what mods were done. I would not recommend using the Bridge card as one could never get the great sound these DS’s can provide. With our External Power Board one can A/B the sound difference by just turning off / on the external supply (the internal supply takes over automatically).

The panel of listeners we had could hear NO difference between the internal supply and external supply so it’s not just my opinion. This was also done with the XS4400 transformers as well as our nickel transformers.

The external supply makes no difference in our listening tests however the nickel transformers along with the Vocm mod makes a huge difference.

We had one member with the external power supply, XS4400 transformers and the Vocm mod that used it for several months.  We changed his transformers to the nickel ones and he was blown away.  He also could not hear any difference between internal supply and external power supply.