Mixing RCA and XLR in same system?

I have a single ended only phono preamp going into a preamp that has both single-ended and balanced inputs. From there I want to use balanced cables from the pre to the power amp. Do the single ended cables limit how good everything downstream will sound? Do the balanced cables from the pre to the power amp make sense? The items in the system are an Audio Research PH3SE phono, an Audio Research tube pre and an Audio Research VT200 tube power amp.
It's my understanding that if your pre and power amp are less than 6' apart, balanced connections are no advantage anyway. But I use my system as you suggested, cd single ended to my Mac preamp, and balanced from preamp to power amp. Sounds good to me.