Dynaco PAS 2 value and difference to PAS 3?

To answer your question, the PAS2 and PAS3 are exactly the same preamp with different face plates and knobs. The 3X has different tone controls, which, if you are actually going to listen to the thing, rather than being a collector, is probably moot, as you would want to bypass them anyway. There was a running change where the output coupling cap in the line stage was increased in value. Again moot, as you would want to increase the value and use a modern film or oil cap. This is a great piece, if you want to learn to work on electronics and hack on gear. There are many inexpensive mods on the internet as well as completely re engineered circit boards by AVA and Curcio. Figure on $150.00-200.00 for the preamp and $100.00 to $500.00 for full mods.

I would respectfully differ on that point based on personal experience. If you jumper the PC-5 circut board, you will avoid all of the crap wire, and solder joints, running to the tone controls themselves. Trace the board and you will see that the signal runs from the board, to the tone controls and then back to the board. The tone controls can effectively take their wipers out of the circuit, but they can't take the wire running back and forth to the board out. Try it. I did on my PAS 3X, and was quite surprised. Not the difference made my bypassing the blend and balance controls, but good none the less.

Just to chime in, if you disconnect the light bulb that serves as a pilot lamp, you will take a lot of current draw off of the power transformer, which is operating pretty hard as it is. Just remove it from the socket. If having no indicator bothers you, you can replace it with an LED. Directions are in one of Frank Van Alstine's bulletins. The time to do this would be when you replace the power supply as you will have easy access to the take off points.

For my money, those orange drop caps sound terrible, hard and splashy. For a few bucks you can crap can them and replace with Russian paper-in-oils or polyprop and tin foil. The difference will not be subtle, IMHO.

The Curcio boards are a complete reengineering of the circuit. I think the others are just new parts in the same circuit.