I am trying to use our Tascam US-1641 with all channels in our church for multi-track recording. I have a Rolls RA62Ah headphone preamp mixer that I am thinking of trying to use to where I can adjust the gain coming into the 1/4" inputs on the back of the US-1641. Can I use this as long as I use stereo cables? And would this be possible to use without damage to the unit? I need to be able to control the gain coming into these channels the first 10 inputs have gain adjusters on them but the last 4 (on the back) do not. Any help or suggestions would be greatly appreciated.