The only good (analog) equaliser I've experienced is from FM Acoustics, they call it a "harmonic lineariser", and empirically, it does not seem to degrade the original signal. However, it only offers a few corner frequencies and is very expensive.
For 1/3octave, may I suggest you consider a software-based solution (as hinted above)? Since you do have a digital signal anyway, you can tune it before it enters the DAC.
A somewhat fussy solution, but probably the most efficient and best sounding -- as these things go.Good luck
For 1/3octave, may I suggest you consider a software-based solution (as hinted above)? Since you do have a digital signal anyway, you can tune it before it enters the DAC.
A somewhat fussy solution, but probably the most efficient and best sounding -- as these things go.Good luck