Not exactly a design question but requires a more knowledgable audience than some other forums out there. Here we go. I have one of these wonderful old Technics stereo amps; massive great thing about the size of an old Betamax video player. Has several inputs at the back: phono, CD, tuner, aux... etc. I want to drive the aux input with my mp3 player, but it's not quite powerful enough so the output volume of the amp is low and slightly noisy. Same problem if I try the CD and tuner inputs. I won't even try doing it with the phono input as even my little player would massively over-drive it possibly causing damage and anyway I believe phono inputs use a RIIA filter to give extra bass boost which would not sound good with any signal other than one from a record turntable. I want to try using sub-min audio transformers (one per channel) between the mp3 player and the aux input to increase the signal levels. Discrete pre-amps of any quality are too expensive so that's why I'm going this route. Anyone see any possible issues by doing this? Will the transformers alter the frequency band of the signals, for example, acting like an unwanted tone control?
thanks