Extension cord advice

Here are the only advantages over an extension cord.

6 outlets that are circuit breaker protected and EMI/RFI noise attenuation.

Are you using a Furman extension cord or a Furman conditioner? If just a cord, since it is just for your turntable & phono preamp, you don't need a heavy gauge cord. Just get a lighter gauge cord (maybe shielded) that will please your wife.

It all depends on if you can hear it or not. Try plugging the turntable & phono preamp into an extension cord only and see if you can detect additional noise. Depending on the design & quality of your preamp, it might be dead quiet with either. If you don't hear a difference, you have your answer.