If you don’t have control over the FOH and monitor sound the board operator can do a lot to let your sound get too metallic, specially if (s)he is already partially deaf and exaggerates the high frequencies.
Some (mostly cheap and affordable Asian mics exaggerate the high mids which can help for some singers but not so much for instruments.
A dynamic mic has typically less highs than a condenser (like the Nadine), so that might help. But a fool at the board can even ruin that too.
Air mics should not be fed in an amp, only FOH and not into the monitors. They can feed back very quickly otherwise.
Contact mics are better, but seldom work with a plywood bass. It css as n be hard to find a good position for it on the top.
Pickups are highly resistant to feedback, the more the closer they are to the strings. Bridge foot to adjuster is the best place if you want a good sound for pizz and arco.
It might be that you need to get the soundpost a bit more away from the bridge foot. Easy task for a luthier.
Before putting much money into that first check if the board operator might be a problem. Get a friend who know how to operate a board or at least checks if the operator follows your wishes of changing the sound and check with him the sound.
I had it once playing with a tango orchestra where the leader thought the bass needs to be amplified that the board operator had no idea of double bass sound and turned the bass up to a very boomy sound. In the intermission I went to the board and turned the bass down, but after a few minutes the boom was there again. I told them in the Soundcheck that the bass frequencies needed to be turned down, but since they ignored me, I simply pulled the plug and played purely acoustical which was no problem at all … except for the operator who checked his board in mild panic what was going wrong.
