Ok thanks! Now to the problem ... I've ruled out pre-amps, faders and operating systems... I can now also rule out upgrades as I upgraded to the latest today.
I have been recording using ribbon mics with Triton Fetheads through pre amps + 1 condensor through pre amp - then to the Tascam ..... all levels correct nothing over loading .
3 tracks in total . 1 Ribbon + 1 condensor on guitar....... then a separate vocal using a Ribbon .
On playback ... everything sounds great..... after mixdown everything sounds great.
I then export to my computer ( I have dual boot with Windows 7 and Linux and have tried both)
I use an online mastering service - Emastered and have already done 2 albums and various odd tracks with them for a couple of years now using tracks that I have recorded on my old Tascam DP01 - so never a problem there....
So I'm getting distortion on the downloaded tracks in mp3 and 24 bit HD wav..... the mp3s uploaded to my server for me to listen to on various computers and Wav burnt onto a Cd.
The first thing I thought was maybe the online service was responsible - but no .... the same problem when I just normalised the tracks first in my DAW and then on the Tascam itself.
I have tried just using condensor mics straight in...... taking pre amps out of the story changing vocal mics ..... changing operating systems in case it was linux.... and the problem of distortion remains ......
It's not the pre's, not the mics, not the online mastering, Tascam updated, what's left.? seriously considering selling this and going back to the old DP01.......