Bass guitar help? 10 pointies?

hey I have a bass guitar. I can tune it by ear, and it matches up perfect with the three tuners i have. but whenever I try to play a song, it is the slightest bit off, and bugs the crap out of me! im not going to buy a new tuner or anything, but can someone explain, if there is a thing on my amp that makes it like that? i have a hiwatt amp. It sounds great, but when i adjust the sound of the bass, it makes it sound the slightest bit off, and again it just bugs me a bit. I haven’t the slightest clue on what to do? i play to Beatles a lot how should i make it sound the most like when Paul plays but in tune?!?!?!

Tagged as: bass guitar, beatles, bugs, clue, crap, hiwatt amp, tuners