Here is the review I posted about the Poseidons with my Khorns on the Klipsch forum. Another winner from Mr Parks!!!
"I've had Shannon Parks DIY Poseidon boards with Jensen PIO coupling caps running for about a week now.
The population and building of the boards is rather easy. With care, a first timer could complete the task in a couple of nights. I bought all the resistors and small parts in accordance with DIY's great bill of material included in the documentation just substituting the Jensens for the metalized poly caps and Uncle Ned's plate resistor values. I also eliminated the biasing circuit on the boards as I had already incorporated an individual biasing scheme in my original build. The only caveat I have for a newbie is to make sure to heat sink the leads on the constant current device in the driver stage as it is easy to damage solid state devices with too much heat.
OK, now for the juicy part. I tested for DC and oscillation, which were fine then I hooked them up to the Juicymusic Blueberry Extreme. I turned everything on and the SOUND! WTF did I do to my amps!!! It was that bad!! After a few minutes, things settled in and the sound became better and better and better until it reached the 72 hour mark from where it has remained the same.
Running NOS RCA 5963 and black plate 12BH7s and GE 6550s the sound is much smoother and more musical than the stock Mark IIIs from which the transformers were donated, the previous Triode Electronics boards and the "other boards" I initially used in both triode and ultra linear modes. The dynamic punch is less than the Triode boards but then, the Triode boards over exaggerated the punch of a kick drum to a rather unpleasant startlingness. The bass is warm and tight, the mids while not as silky as DHTs are excellent. The highs are clear and pleasant and extend well beyond my hearing.
All in all, I highly recommend the Poseidon boards for anyone planning an upgrade to some Dynaco Mark IIIs or a bottom up build using aftermarket transformers."
Rick