I agree and disagree. It is possible to do a good mp3. But a flac file will always be better. As to your comment on tubes, you may be correct, but they are only used as preamps on the units i have chosen. They are well implemented, and have over a 200v supply, not just being used as a noise filter. They do offer some coloration, but total thd is well below 1%. If a car is in motion, you will not be able to hear the difference, but in the correct setting, mp3 is decernable from flac. The setup i have is only limited to the recording, it is capable of prodcing beyond the spectrum of hearing in both directions, but you can detect upper and lower end roll-ffs. Early mp3 rolled off way to early to compress the files. When your ribbons dont start rolling off till 40k and have usable responce to 60k, you want the recording to hold up. Dont forget, the audio itself is only half the battle. We are all after some degree of bragging rights, or we wouldnt have adopted the empeg. BTW, with car audio, measured system response and accuracy is part of the judging, not just subjective listening tests.
Hans