You should defintely be using an external master word clock when tracking or mixing with more than 2 units.
You want each box to reference the same clock, otherwise each will run on its own internal clock and there may be ugly digital noises like pops and clicks, or otherwise muddy sound when you playback the audio. This is crucial!
Especially seeing as though they are MOTU units which don't have very good internal clocks to begin with. You can get significantly better results out of those boxes by clocking them with something like a Lucid master word clock.
I should know - I have a 2408mk3 and a HD192. Niether was remotely close to my Apogee Rosetta 800 until I started clocking them to the Lucid. Now the HD192 has a cleaner sound. The 2408mk3 sounds better - but theres really no helping that box. Now, the tracks recorded with the MOTUs at least blend better with the Apogee tracks.
I'm actually reconfiguring my studio and have found an alternative solution to using my Lucid SSG 192 - just clock my HD192 from the Rosetta 800. So I'm selling it on ebay here:
Lucid SSG 192 Master Word Clock Auction
This is would work perfectly for you and its still at a low price.
Someone's gonna win it soon!
cdog
