If the condenser requires phantom (which most do) then they simply will not work if the phantom is dead. I find that I have to run my pre's pretty hot with my condensers. A dynamic mic (57 or 58 for example) I run about 1/2, but with my condensers I have to be up around 2 or 3 o'clock. (I'm just saying that as a point of reference)
You mention Sonar has a low level, but how do the levels look on the VS-100 meters? Keep in mind that if Sonar is set to 24bit, the dynamic range is huge. What would normally peak out a 16 bit recording will register much lower (approximately 12db less). This is perfectly normal, and you can record at that level (if it is 24 bit) without losing any quality. With 24 bit there is no need to record hot - it is better to leave it some room.
Just my 2 cents - good luck!
Don't fix it in the mix ... Fix it in the take!
Desktop: Win 7 Pro 64 Bit , ASUS MB w/Intel Chipset, INTEL Q9300 Quad Core, 2.5 GHz, 8 GB RAM, ATI 5450 Video
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