Error: unexpected end of file at offset....

[mars51]

Thanks for the quick response, Simon. It wasn't the answer I wanted because the conversion will take a very long time. I thought that JRiver, which I've been on since MC17 in Win & Mac was my salvation after iTunes & PureMusic. How wrong could I have been? Grrr. Here's 10 random selections of .aiff from different albums.

Error: unexpected end of file at offset 47222035 in file Steve Baughman/Celtic Fingerstyle Guitar Vol. 2 - The Blarney Pilgrim/2-05 Fanny Power.aiff (length 47222035)
Error: unexpected end of file at offset 37385039 in file Eternal Jazz Project/Seasons/08 Don't Talk to me in the Morning.aiff (length 37385039)
Error: unexpected end of file at offset 42932681 in file Lara St John/CD1 - Bach - The Six Sonatas and Partitas for Solo Violin/04 Sonata No 1 in G minor BWV 1001 - IV Presto.aiff (length 42932681)
Error: unexpected end of file at offset 21631038 in file Richard Wagner/Siegfried Disc 2/2-01 Aufzug 1 Szene 2 - Nach eitlen Fernen forschest du (Wanderer).aiff (length 21631038)
Error: unexpected end of file at offset 41883385 in file Vaughan Williams Collector's Edition disc 19 - Sacred Choral Music/19-02 Mass in G minor_ Kyrie.aiff (length 41883385)
Error: unexpected end of file at offset 254150535 in file Philharmonia Baroque/Beethoven - Opferlied and Symphony Number 9/05 Symphony No 9 in D Minor Op 125_ Presto.aiff (length 254150535)
Error: unexpected end of file at offset 338698847 in file JAZZ MUSIC/Chick Corea_Gary Burton_Pat Metheny_Dave Holland_Roy Haynes/Like Minds/04 Futures.aiff (length 338698847)
Error: unexpected end of file at offset 59531843 in file JAZZ MUSIC/Anthony Wilson Nonet/Power Of Nine/02 I And Thou.aiff (length 59531843)
Error: unexpected end of file at offset 248659991 in file JAZZ MUSIC/Nicholas Payton_Bob Belden_Sam Yahel_Billy Drummond_John Hart/Mysterious Shorter/07 Beauty and the Beast.aiff (length 248659991)
Error: unexpected end of file at offset 43593111 in file JAZZ MUSIC/Art Pepper/Art Pepper Meets The Rhythm Section [Bonus Track]/05 Straight Life.aiff (length 43593111

I was wrong, now I look I have a host of .flac issues but NONE of them are 'unexpected end of file...' issues, they relate to TYER, playlist & ALBUMARTIST etc etc. 3000-odd error & warning messages is quite a shock.
Can anyone tell me, is it quicker to convert .aiff to .aiff than .aiff to flac? I tried a couple of albums to .flac and it was slow on dBpoweramp on Win8 but I was doing over the network on the NAS. Having been burned with this Jriver/.aiff, I feel like standardising on .flac. I guess it's quicker if the file is local (on a HDD). The quickest converter is? I have both Win & Mac decent spec machines.
Thanks
Martin