Musiclover,
I might be well off base, but before I went all digital, I connected my phono preamp to my Don Sachs preamp by way of one of the inputs on the Sachs preamp. That is assuming you are using the R300 as an integrated amp. TT > phono preamp (with no volume control) > preamp > amp > speakers. With the R300, it would be TT > phono preamp > R300 > speakers. I can't see why the R300 remote wouldn't function normally.