Dynaco ST-70 vs Mark 3

Is the basic sound quality better in a ST-70 or a Mark 3?  Other than the ARC ST-70 mods, are there any specific mods that significantly improve the sound of either one?  


The ST-70 has long been considered the better sounding amp.

The important thing is to make sure its power supplies (including the bias supply and its rectifier) are operating properly. The often need resistors on the circuit board replaced too. Nice coupling caps really help it out; try the V-Cap ODAM part. You can replace the rare and expensive 7199 with a 6GH8A (which gives you lower distortion) using this adapter.


     Joe Curcio was my go-to guy, whenever I needed suggestions on upgrading Dynaco gear, back in the day.

                          Still great sounding gear, when updated.