I bought my Dynaco ST70 from Bob assembled with all upgrades. The sound was very good. I tried different tubes during this time. I found that the sound best for me with Mulard CV4024 and 6P3S-E Russian tubes. Then I decided to upgrade all parts. Because, as it turns out each element have affects the sound quality.
I began by coupling capacitors Mundorf Silver/Gold in Oil and most resistors Caddock MK132 and Amtrans AMRG. The result is impressive. Full sound, from low to high. That stimulates me to move on. I did a lot of orders from Partsconnection. I changed all the other resistors and capacitors. I used 220uf MUNDORF M-Lytic HV + additional capacitors in the power supply after the choke. On VTA board i put Nichicon KX 100and150uF 450V and ELNA Silmic II 100uF/100V very good improvement. Very important for sound are resistors R44 and R39(not only) - AMRG in this position are fine.
I changed the internal wiring with Kimber TCSS hook-up wire (very transparent sound).
I many wondering what resistors to put on R11, R13, R19 and R21. I chose Kiwame, but I'm not sure this is the best choice.
For amplification I use shunt attenuator scheme with 15k TX2575 shunt resistor and 50k stepped Attenuator.
I changed input RCA with Vampire CM1F/CB and binding post with CMC 858-S-CU-G Pure Copper Gold platted. I replace and fuse holder with ACME cryo silver platted. I put Oyaide R-inlet for possibility to try different power cords.
Now sound is rich, fuller and sweet. I am satisfied.
Hire is pictures from my baby.
PS: sorry for my english