Elma make the switching part, for example the Goldpoint attenuators use the Elma switches, but add their own PCB's and resistor layouts to make the complete attenuator. Anything using Elma switches gets a thumbs up from me.
There are different types of attenuator, main ones being series and ladder. Personally i don't like the idea of series attenuators as you end up with a whole string of resistors in the signal path, where as with ladder style there is only ever two resistors in the path creating a divider. Easy to spot the difference as the ladder style have double the amount of resistors.
Then there are resistor choices, much like brands of coffee or beer everybody will have a preference. Kiwami are carbon resistors, i think they are carbon film as opposed to carbon comp. Personally i find them a little soft sounding, rounds the edges off and makes things all smooth and cuddly. Where as metal film i find to be more transparent so you don't notice them. I've always use Dale RN series resistors in signal paths and attenuators for that reason, but again that's just my opinion, i may be completely wrong about that.
I believe 50k will work fine, especially with something like a Modi driving it as it will have been designed to drive 20k-50k loads.
