Replace resistors with carbon-comps and caps with paper-in-oil, as much as possible.
If using tube gear; pick NOS valves, manufactured in Britain.
Always worked for the few customers of mine, that were so inclined.
How do you add color?
For those of you who are adherents of straight wire, ruler flat frequency response, accurate and neutral sound, artists’ true intentions, etc. ... please stop reading now. You’ve been warned. If you continue to read, you might get heartburn and since I’m a nice guy, I don’t want to do that to you.
Now, for those who are not opposed to adding a bit of color and flavor to tune/tweak the sound to their liking, what is your preferred method of madness? Speakers, amps, preamps, DACs, cables? I know many who like the combination of solid state amps with tube preamps. Lately, a lot of upmarket DACs are using tubes (Lampizator) or R2R to add a sort of tube-like flavoring. Let’s say you’re happy with your solid state amp but want to add a bit of tube magic to the chain, would you get there by way of tube preamps or tube DACs? Or both -- which might be too much of a good thing perhaps?