I have a few questions about the DT770's. I'll be using an active P>sansamp>Apogee Duet>macbook Pro>Logic Why the huge range in price? (ebay BIN for $150 retailers for $250+) Are there different models/lower quality versions? Can an apogee duet power these? (80ohms) Should I use these to record really great sounding basslines? Vocals? Guitar? Is it really worth even $150?