A while back I made a board for the Crack with a switch that changes the bias resistors for optimal current for 12AU7, E80CC, and 12BH7 tubes. I continue to get requests so I decided to get more boards made and offer them to the community. Here is my
original post for the board I made. I'm offering bare boards for $6.00 shipped in the US ($10.00 international for most countries) and if there's enough interest in kits, I can buy parts in quantity to get a discount. I'm thinking +$10 with parts. So, $16 shipped in the US and $20 for int'l for kits.
The new boards are blue: