OK. advantage to A10's solution is that it is simpler, and it is adjustable in the sense that you can adjust the gain reduction by increasing the value of the resistor between the volume control wiper (Center tap) and ground, or across the input jack. It is also cheaper, because it only costs the value of the resistor, which will be about a half a buck each, at worst. But, once you have picked the resistor, you are stuck with the "adjusted" gain and if you put the resistor on the volume control, you adjust the gain downward for ALL inputs, including the phono section. Also, if you put the resistor on the input jack, you are adjusting the impedance of that input down, and it may affect the response of the source you are plugging into it.
My suggestion costs about $20.00 by the time you are through with it, and requires some considerable work to build it. BUT, it is infinitely adjustable from no attenuation to killing the input dead, and you can change it depending on the signal level coming out of the source. There is also the disadvantage that my alternative takes up more space.
So, it's whatever you want to do. I like my solution and I build these things all the time. It's what I would do when confronted by this problem. But thank you to A10 for suggesting his alternative, which I didn't see at all.
And good luck from that unseeing, but agreeable old purveyor of disagreement,