The Rosetta 800 has 8 channels of +4 Db balanced outputs on it. Have you set up a digital link from the 002 to the Rosetta to use all 8 channels? If so, you might want to have a mixer so that you can run stems out and experiment with mixing outside the box. Another possibility is to set up surround sound monitoring system and run six channels for Left Front, Center, Right Front, Left Rear, Right Rear and Sub Woofer channel. You have the capability, it might be fun to use it.
If it did not come with the Rosetta, you will need a DB-25 connector to the 8 analog outputs, probably going to XLR male connectors. If it were me, I'd also use the Rosetta for any inputs I might need.
If you are only running channels 1 & 2 for stereo, then you will want to patch it direct into the Bryson. I think your DAW and I-Tunes will both have software volume controls for monitoring which will allow you to control volume (primary use of a preamp). The Rosetta will easily push the Bryson as loud as it will go. Remember to have mercy on your speakers and ears!
Most consumer preamps will not have the headroom (-10 dbv reference standard, hence 14 db less output compared to the Rosetta assuming the same headroom before clipping, which I think the consumer preamps probably would not have as much as the R.) to keep up with the Rosetta and should NOT be put in line with this signal chain. They will clip early and do harm to your monitoring chain.
The only thing which you might still use the consumer preamp for would be the phono input. In this case, you should get a consumer preamp (anything which meets your standards), and unplug the computer (aka Rosetta outputs) from the Byrson and plug in the preamp (when the Bryson is OFF!), listen to records, then turn off the Bryson, wait for the capacitors to discharge (i.e. no more sound comes through the amp) and repatch the Rosetta.
Let us know if there is anything I missed on this, or if you still want to spend more on the system for some other reason. The way you have currently described it, it seems that any recording money you have would be better put into other areas.
Galil