Just a heads up, the cardinal is a little trickier than the average build.
1. It uses 3 2n5457 jfets. It's hard to find legitimate ones in the through hole package (probably don't trust eBay). I used smd with a conversion board.
2. There are some trimmers that need adjusted based on taking some measurements.
3. The build doc is super long and detailed, but you learn a lot.
4. It's strongly recommended in the build doc that you use premade vactrols instead of making your own led/ldr combo, so it's more expensive than your average build.
All that said I think it was worth it. Mine fired right up without any issues and adjusting the trimmers according to the directions was pretty easy. Sounds great too.