If the PS Audio has PerfectWave DirectStream
(I have seen them with a “Badge” on the right)
In white letters stacked like that on the left backside one above the other
Is that an older model ? Is it a MK1 Direct Stream or just a PerfectWave
Thank You
IIRC, the PerfectWave DAC (sans the DirectStream moniker) is the original PerfectWave DAC. Next up was the PS Audio DirectStream Sr. DAC (a/k/a the DirectStream MKI).
That was followed by the DirectStream DAC MK II.
Welcome to the nut hou…er um, the forum.
Yes John, welcome!
Just to add to what scotte1 wrote, I started, way back when, with the original PerfectWave DAC. If I remember correctly, PSA offered a hardware update kit for it, which I purchased and upgraded the unit myself, but it was still a ‘PerfectWave DAC’. Then the DirectStream DAC came out. The hardware was very different from the PerfectWave. PSA did offer an ‘upgrade kit’ but it was virtually a complete rebuild. I think only the front display was retained! I went ahead, purchased the kit and again did the upgrade myself. They did provide a ‘DirectStream’ logo so you could hide the ‘PerfectWave’ one. 
When the DirectStream MK II came out, the older one (upgrade kit or original unit) came to be known as MK I. At least that’s how I remember it. 