Opinions on PS Audio Direct Stream DAC (Mk 1)

As well as power, interconnects matter - low impedance/capacitance helps since the Directstream has transformer outputs (without really good interconnects a preamp will make a bigger difference).  Also depends on the input sensivity of your amps.  Keep tweaking and you’ll get more out of it.

I'm using a knock-off Nordost Gold PC that I've really liked in other applications but I'm also just using a standard HDMI cable (tho a pretty decent one) for the I2S connection, so that's a potential weak spot I can experiment with. XLRs to the amp are Zavfino Fusions and I've liked them a lot in every application I've tried.

I do have some other DH Labs Power Plus PCs I can try as well.

@shooter41 try DH Labs. 

Further update... I'm loving my DirectStream DAC at this point. 

I mainly listen to classical, so there is emphasis on beauty of timbre as well as musical expression through macro- and micro-dynamics. The DSDAC renders the subtle phrase dynamics beautifully. 

I listened to a Beethoven piano sonata performed by Barenboim, who is a monster player, and it was thrilling. Barenboim's interpretative choices worked especially well compared to other DACs... and his highly dynamic playing was evident. He was committing violence on the piano and the DSDAC revealed it all.

The resolution is stunning. Hall ambience decay times, following the cutoff of the last note, are very extended.

Only problem: the softer bass instruments can get covered up by the midrange and lose their pitch. If a bass instrument has a lot of harmonics, sure you can hear it clearly, but if it's a bass guitar (without distortion) or double bass and it's not playing forte it just gets lost under the midrange and the pitch disappears. This is a pretty significant problem as a lot of classical music recordings are unnaturally light in the bass (apparently those recording engineers aren't bass heads). I'm hoping the bass will improve with burn-in.

Regarding cabling, power, etc.

- I use parallel capacitance for power conditioning, using boxes that plug into the wall. They have 10 uF capacitors, chosen for best sound by Igor, between hot and neutral, hot and ground, and neutral and group, so 30 uF each. I have about 12 of these boxes around my apartment, giving 360 uF of parallel capacitance, but that doesn't count the system circuit, which has another 100 uF between neutral and hot, and hot and ground (the system circuit skips the neutral-to-ground caps to avoid hum). I use power cords by Igor, which he sells for $850, and the other members of the NJAS say it would take $3000-5000 to duplicate their performance in stock items. I use interconnects without a traditional shield, but instead use ERS fabric to absorb RFI. They are low capacitance given that they don't have a shield. 

I also have the DSDAC as well as my Aurender N100 sitting on a vibration damping solution created by Igor... squash balls sitting in little cups filled with damping material. His experiments showed him that pneumatic support sounds best, and squash balls work perfectly as long as you sit them in a little dollup of damping material to inhibit resonance modes within the rubber walls of the ball. The DS DAC and the Aurender are each sitting on six squash balls. 

With that particular DAC, using an I2S cable was a very smart move on your part!