Quoc -- you gotta love those vintage EL84 amps! I have the Pilot SA-232 also and it is really sweet. The Eico HF-81 has had some good press lately. Mine has been in the family since my uncle built it in 1959, still sounds great!
But for the original poster, stay away from the Welborne kit if you are not skilled at reading a schematic. I hear the new ones have better instructions, but I'd be wary of it. I'm anxious to try the K&K mod sometime. I love Kevin's phono pre.
Another ST-70 board that has been well-reviewed, and is a simple drop-in installation is the one offered by Maple Tree Audio in Canada. It uses octal tubes, which are right in line with the lovely classic sound of the Dynaco. On the other hand, I would strongly recommend a power supply upgrade at the same time you do an input board. Check out the Dynaco forum on AA where you will see lots of help and advice.
But for the original poster, stay away from the Welborne kit if you are not skilled at reading a schematic. I hear the new ones have better instructions, but I'd be wary of it. I'm anxious to try the K&K mod sometime. I love Kevin's phono pre.
Another ST-70 board that has been well-reviewed, and is a simple drop-in installation is the one offered by Maple Tree Audio in Canada. It uses octal tubes, which are right in line with the lovely classic sound of the Dynaco. On the other hand, I would strongly recommend a power supply upgrade at the same time you do an input board. Check out the Dynaco forum on AA where you will see lots of help and advice.