If I imported a CD as 128kbps m4a files and then convert them to 256kbps mp3 files, will the mp3 files be a lower quality than if I had originally imported them from the CD as 256kbps mp3 files? Thanks.
Since your converting a 2nd time to quite a high bitrate, there will be some loss but not too much. I've done it myself before when I no longer had access to the original source. Try it and let us know how turns out. If you had gone straight from CD to 256Kbps mp3, the mp3's would be better.
I'd convert using a VBR profile of 96 to 256 Kbps. That way your output file will use only as many bits as needed.
Thanks for the responses. I have converted a few and I really can't tell a difference except in my car, which doesn't play m4a at all, and mp3 CDs made at 128 begin skipping after a while but not the CDs made at 256. I haven't quite experimented with enough constants (blank media, original source, etc.) to positively narrow it down to the bitrate, but it does seem correct the issue. Thanks again.