In rec.audio.pro, "Scott Rolston" wrote:

Can you get a good sounding mix on the cassette porta studio?

That's another point, if you've got the original 4-track tapes and
the original recorder (or another that will play the tapes), mixing
down again (to the DAT and/or the 2496 card) will sound much better
than the stereo cassette mixes you're trying to transfer now. Anything
that can remove a generation of cassette recording is a no-brainer.

Doesn't the Audiophile 24/96 have the same -10/"consumer"/+4 input
level switching as the Delta 66? Run the M-Audio control panel and
change the inputs to "consumer" or +4, and see if that fixes your
problem. Another pane also has peak-showing meters for the inputs, and
will go into the red for clipping. Make sure it doesn't go that high.
If the level-switching doesn't fix it, make or use inline attentuators
("pads") as Scott (Dorsey) was suggesting.

Mix what
sounds good to you and master on DAT. Bring this mix in spdif to computer.
Hey, you already mentioned
the other options, so thought I'd throw this one in for good measure. : )

Scott