Al, you, Lew, and many others are way above my knowledge of electronics. But as I understand this one can load down but not up.
Therefore, changing the hard-wired input from 47K to 100K still allows it to be loaded down to 47K (with parallel inputs or Y adaptors) as well as 1K, 470, 40 ohms, etc., to find the best match for a given cartridge. But one cannot upload from 47K to 100K or any higher value.
Indeed, a few older preamps provided switched loading and included 100K as an option.
I'm a strong believer there are no best/single answers in this hobby, too many variables. So it usually comes down to trying any option for ourselves in our own system. It seems changing the phono input to 100K simple gives us one more option.
Therefore, changing the hard-wired input from 47K to 100K still allows it to be loaded down to 47K (with parallel inputs or Y adaptors) as well as 1K, 470, 40 ohms, etc., to find the best match for a given cartridge. But one cannot upload from 47K to 100K or any higher value.
Indeed, a few older preamps provided switched loading and included 100K as an option.
I'm a strong believer there are no best/single answers in this hobby, too many variables. So it usually comes down to trying any option for ourselves in our own system. It seems changing the phono input to 100K simple gives us one more option.