MY PREAMP IS A MINGDA 300PRE WHICH HAS 2 PAIRS OF OUTPUTS
THE WILLSENTON R300 AMPS HAVE PRE IN ONLY
Is this your Willsenton R300 amp?
If that is your amp, it is an integrated amp.
I can not download the manuals as this is a piece of Chinese you know what, and there manual download site is not working.
Is this your Ming Da 300 preamp contraption?
If those are the units we are talking about, then you are way of course.
Both of those units seem to be grossly overpriced and not much use for what you are trying to do.