I installed the "VSM" mod kit by Richard S. Mogovaro in a later vintage FM-5 that my kid now uses. Difference in FM-5 was notable! Better channel separation and "highs" (switchable demphasis 25/75uS, no 19KHz filters, upgraded components on add-in board, etc. Without the mod the tuner is a much lesser species. Richard Modaferri is (I believe) still active in Califirnia - reputedly an ace of tuners. Maybe ou can find him in an internet search. I have three FM 5 tuners (one with the PPM -5 RIAA equalization board for phono input in place of the line input). I agree with the comment that this early solid state tuner was not the most musical. However, for the money, used, it is quite a buy. The AR tuner, almost the same vintage, was a more musically satisfying tuner (orig. board was made ijn W. Germany, as I recall). Years after production the Boston Audio Society still raved about it. I have one (dual voltage) that is great and have a second with problems and sold my 1971 AR tuner to a friend who still uses the pretty unit. The Dyna FM-5 lacks the same sleek look.