The site is DIYParadise.com. Once you get on there look for the 5687 based tube DIY pre-amp. You will see what I mean, they spell it out pretty thoroughly. Actually the 125$ price point; now that I look at it seems a little high. More like 80-90$. There aree many people who have built both the pre-amp and amp. The amp uses the same tube as an output tube and people build it SE or Push-Pull. On the site they compare it to a Foreplay.