Yeah, I've subbed 1n4001 and 1n914 (or 4148, whatever) and I think they sound great. I heard that's what's in the current KoT as the original spec are getting too hard to source.
Interesting fact, I have a Paragon Mini with the "proper" diodes and..... it's not great imo. I suspect I've put an incorrect capacitor in there somewhere as it's quite flabby.
