iTunes Match. Help

- multiple albums in my collection not 100% matched. i.e. 3 songs of 10 "uploaded" creating audio variances when played. For Example if I listen to Led Zeppelin's first album, 2 out of 9 songs are "matched". So when I access this album from match on other computers, I have most of the album at 128kbps and 2 matched at 256kbps. They sound much brighter and louder. Why isn't the rest of the album doing that?

This is just one small example in my vast collection. many many albums are featuring this issue.

Any Match experts out there who can assist with this?

BTW- I own the cd, but no longer have ability to import through computer because all new computers seem to require an external drive - otherwise, I'd try deleting and re-importing.