30 ft rca run too long for a phono to preamp?

I would first do everything possible to make things work for the turntable at its current location. If this is not possible, I would suggest moving the preamp along with the turntable to the new location. The phono stage's voltage output (at line level) is not so much the issue but rather, the preamp (line stage) output stage is likely to be able to better "handle" driving long ICs to the amp than a phono stage's output to drive the same ICs to the line stage input. But still, there is no guarantee this will be a success.
John

Have read fairly consistently that after about 15 to 20 feet, some say longer, a balanced interconnect is better than an RCA. If you have to go 30 feet, go for balanced, if your pre-amp allows for it,though you can get balance to rca adapters, but that just adds one more chain in the link, where to my mind the shortest link works best with the fewest connections works best.

I think total capacitance would be way too high.

30' is getting into an iffy range even for line level signals, where I've seen balanced cables recommended for anything over 10 meters.

Both components have only unbalanced connections.

Thirty feet is really pushing it, but fortunately the phono stage output impedance is only 100 ohms (which in fact is considerably lower than the preamp's output impedance of 440 ohms). That should be low enough to eliminate the possibility of upper treble rolloff due to interaction of cable capacitance with the output impedance.

The remaining concern would be noise pickup. There is no way to predict that other than by trying it, since it is dependent on the noise environment of your particular setup. But in addition to the noise environment, success or failure would be dependent on the quality of the shields in the particular interconnects you would be using (both shield coverage and shield resistance), so I would try, if possible, to arrange trials of several different cables, with return privileges.

Regards,
-- Al