What has better mic preamps?

The best way to tell is to do a shoot out on the things you'll be recording most often. Those are 2 totally different products, 1 with 2 channels and the other with 24 channels. You can also divide the total cost by number of channels to see the rough break down of how much each pre is worth. Though conversion, EQ and other features are also need to be considered.
 
Don't they call that string theory? The duet probably has better pres, but whether you would even hear the difference is debatable. Most Burr-Brown based cheap pres are damned similar.
 
What would have a better sound - a Allen & Heath ZED 24, or an Apogee Duet 2?

The Allen & Heath Zed 24 is primarily designed for live sound. The church I used to attend has one and for the two years I was running the sound, I found it to be a workhorse and the pres are very good. I never had to have the gains on the pres set at more than the 12 o'clock position.
Never having used the Apogee, I can't offer a comment or comparison. Hopefully someone will weigh in who has experience with both.
 
Back
Top