cable break in phono stage to preamp

Provided you have a CD player that uses the same connector (RCA or XLR) I suggest you put your cable there for break in. The phono stage produces almost no output unless you play an LP and allow the signal to pass through to the preamp.

CD players have adequate output and you can listen to the music as you break in, or allow it to build hours in silence. Either way it will get the job done.

"Is keeping my phono stage on all the time adequate enough to break in the cable between the phono stage and my preamp?"

No, you need to have a constant signal running through it. Do what Albert suggests.

You may want to consider some AQ cables with the dbs option. They're great for TT's. With the dbs, the cables break in faster and stay broken in for longer periods of time.