twenty five 1M varaible resistors

individually controlled via digital pots. six specifically assigned and one that can be assigned to any other resistor via up/down switch. used for audio so needs to be clean. is this possible in arduino? thank you!!

1M is generally too high for audio signals, you'll have noise issues, both thermal and pickup, and perhaps crosstalk too.

You are asking for 25 digipots controlled from one Arduino perhaps?

Perhaps log-law digipots with zero-crossing detection for minimum switching artifacts?

What are you trying to do?

You need to look at the circuit you are installing the pots and verify that you are at the correct impedance for the pots. If not it will inject more noise then the pots by a large margin. It sounds like your resistance is very high for a transistor based circuit although in range for vacuum tube designs. Also is it an analog or control signal that is going through the pots. Control signals will inject a lot less noise. There are many different materials to chose from, and most have audio taper available. Do you know how to do analog design and specify the parts you will be using. The pots are only a small portion of the circuit. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil

used for audio so needs to be clean. is this possible in arduino?

Can you supply actual details of what you are trying to do, the phrase used for audio has many different meanings so it doesn’t help much.

its for voltage dividers mostly. variable tube amp circuits.

MarkT:
1M is generally too high for audio signals, you'll have noise issues, both thermal and pickup, and perhaps crosstalk too.

You are asking for 25 digipots controlled from one Arduino perhaps?

Perhaps log-law digipots with zero-crossing detection for minimum switching artifacts?

What are you trying to do?

i want to have something like this with the ability to change resistor values. shift registers and relays/optos for the capacitors.

I doubt that you would be satisfied with the operation
of digipots because, being digitally controlled, they
"jump" from one value to the next. They do not change
value smoothly. Also, since the application is for low level
audio, you may hear the effects of the digital control
signals.
Herb

jumping is fine and isolation would be necessary. what are my options?

You do realize that there is several hundred volts between 'X' and 'Y', right? How much voltage do you think a digipot can handle? For R12, for example?

Digipots <==> Valve circuits.

No!

Maybe look at having a servo drive a pot. That is the only way I could see this working.

gtrboy:
individually controlled via digital pots. six specifically assigned and one that can be assigned to any other resistor via up/down switch. used for audio so needs to be clean. is this possible in arduino? thank you!!

And then you said:

its for voltage dividers mostly. variable tube amp circuits.

No, absolutely not possible.

A clear demonstration of why it is much better to give full information up-front.

Digital pots are typically rated upto 15V or so, orders of magnitude too small for valve circuitry.