I don't know, so hopefully someone who has used an old 2408 can jump in. I do use an 828X, but that is new and has pres - which I don't use. It works well to feed ADAT.
In trying to find out more about that 2408 I found that MOTU has a list of user manuals here:
MOTU.com - Product manuals
But the MKII is too old to be listed. The MKIII is there. It may be close enough.
And I found an article about the 2408 in SOS Magazine, from 17 years ago, which means the 2408 came on the market some time prior to that.
MOTU 2408
It says:
"The converters are full 20-bit devices and the internal signal path is 24-bit with support for both 44.1 and 48kHz sample rates. Word clock in and out allows integration into systems driven from a master clock"
It also says:
"To complete the package, the necessary support software comes on CD-ROM along with a Mac-only application called AudioDesk. This is very similar to the audio side of Digital Performer v2.4 and offers recording at up to 24-bit resolution with 32-bit processing"
I wonder if that is too old.
Do you have access to one to try? Grab a TOSlink cable and give it a go. I have no idea about the quality of the ADC from back then, but suspect something newer will sound better.
I had an AKAI, DPS24 from about 14 years ago. I never could get it to sync well with the Apollo. It would give me pops and crackles.
:- Don