the roland 880 and 880ex do not supply phantom power, which you will need for any professional condenser mic. the 1680 does have xlr inputs and phantom power, but the pre's in that unit are not quite of the quality you might want. most of us who use the roland workstations use outboard mic preamps with phantom power, and outboard compression, since the compression circuits in the rolands come after the ADA converters, so you might introduce digital distortion before ever getting to the compressor. all three of the mics you mention are pretty good entry-level large diaphragm condensers. i owned a pair of the c3000s for a while, and have used the 4033 on several occasions. all of those mics have a significant upper frequency lift that works well for acoustic guitar, but sometimes adds too much harshness for vocals, especially in a digital environment. you can warm up the mics a little by using a tube mic preamp, but the less expensive tube preamps often add a gritty sound that doesn;t really help much for vocals. often female vocalists do better with a warmer mic to start with - a good ribbon mic, tube mic, or even a large diaprhragm dynamic such as the sennheiser 421 or EV RE-20 (like broadcasters use). try to avoid EQ as much as possible - much better to start with the right mic.