Preventing PowerShell from wrapping value types in PSObjects

I have a .NET API that uses a lot of delegates. My API has a couple methods similar to the following:

public static class MyClass
{
    public static void DoSomethingWithString(Func<object> myFunc)
    {
        string myStringValue = myFunc().ToString();
        Console.WriteLine(myStringValue);
    }

    public static void DoSomethingWithDouble(Func<object> myFunc)
    {
        object unparsedValue = myFunc();
        double parsedValue = Convert.ToDouble(unparsedValue);
        Console.WriteLine(parsedValue);
    }
}

Now in PowerShell I have the following:

[MyClass]::DoSomethingWithString({ "Hello" }); # No error here
[MyClass]::DoSomethingWithDouble({ 123.4 });   # InvalidCastException - can't convert a PSObject to double

The problem is that my PowerShell scriptblock is returning a PSObject instead of the actual double value. My .NET API doesn't know anything about PowerShell, and I don't want to add a reference to PowerShell DLLs just so I can add special handling for this particular scenario.

Is there a way to get my scriptblocks to return actual value types rather than PSObjects? Or is there a PowerShell-agnostic way for my .NET library to handle PSObjects?