I currently have a PTIII system and a Mackie 8 Bus mixer. What will I gain by using an outboard mic preamp. My current vocal mic is a Rode NTK. This is a tube mic. I bring it into the Mackie and out though the 888 into PT where I add compressors etc. I don't understand everything and desire to learn from the masterminds here. What will I gain? What should I look for? What is the best sub 1000.00 choice and is it worth it? Thank you.