You're on the right track. But...
Good luck finding a USA supplier that actually has a good quality conductive plastic element, 4 gang pot @5K ohms.
Let alone the Alps brand.
I inquired directly at the ALPS USA website and never got a response.
If you are looking for one part just for yourself, you are going to run into problems of miminum quanties that many suppliers demand. Anywhere from 10 units to 100.
I need to be specific here: 4 GANG, CONDUCTIVE PLASTIC, 5K.
There are many helpfull suggestions if you search the other forums but I found most of them were skewed towards either expensive stepped attenuators (from $50 to $200) or compromising the project by unbalancing the output and using 2 gang pots.
Neither option was viable for me either from a price standpoint or operationaly. I'm not saying that unbalanced operation is wrong.
But for me the whole point of the design is to gain the benefits of balanced operation at an affordable price. My sources have balanced outputs, my amplifiers have balanced inputs and my cable runs are going to be longer than usual.
I want balanced operation hence a 4 gang pot at approximately 5K to be used at the output of the preamp is essential.
Let me know if you come across the rare beast!