I have a design that uses multiple modules, but I am at a stage of rationalizing components, for weight, size, and cost.

My initial layout is as below.



This shows multiple DCDC psu's, which I want to rationalize. So I thought multiple MOSFET's would be the way to go.
So the following image is my thoughts.



But I am looking for guidance on turning this into the real world, as per image below. Any thoughts plz

And the values for resistors Ra and Rb for 30v and 60v Vcc. The MOSFET's I use and planning to use are P channel IRF9540N (because I have lots of them) which are good for up to 100v. The loads are in the 1Amp range.

The MOSFET with 12v signal and 12v Vcc works fine with a 12k resistor.

 

You go straight into details without ANY big-picture context?
What is this thing? What does it do?
Why are you trying to switch the amp's power?

 

You go straight into details without ANY big-picture context?
What is this thing? What does it do?
Why are you trying to switch the amp's power?

In addition to Sensacell's question, the statement "to rationalize the circuit" does not convey any meaning to me. In fact, the block diagram, while being easily legible as to blocks and signal, also makes very little sense.

What we need is an explanation of what the final result of the request as far as operation, control, controls, and function. At that point we may be able to describe a path to the goal.
Clearly " gray-b" understands, but clearly I do not understand yet.

 

The MOSFET with 12v signal and 12v Vcc works fine with a 12k resistor.

You've drawn JFETs.

It would also work with 10k, 20k, 1k, ... They're just pulling up the gate so the MOSFET can turn off. The actual value required depends on the sink capacity of the 12V signal and how many MOSFETs you're driving.

1. Does the 12V signal alternate between 12V and 0V? If so, you need an inversion of the 12V signal.
2. How much current can the 12V signal sink?
3. Vgs(max) is 20V, so you'll need some zener diodes in addition to pull-up resistors.

 

Normally one would not disable part of the circuit by switching off its power supply. It leads to all sorts of unwanted transients (and clicks and pops if it is audio)
Why are there two power supplies for two amplifiers? Won't one power supply do the job?
Why not turn off the output by gating the input signal?

 

And the values for resistors Ra and Rb for 30v and 60v Vcc. The MOSFET's I use and planning to use are P channel IRF9540N The loads are in the 1Amp range.