Question on phono input noise levels

Earlier this year, I had my Parasound P5 Preamp connected to my 35+ year old Bang and Olufsen turntable, with a moving magnet cartridge. I noticed that with the turntable connected (including the ground wire) I noticed quite a bit of hiss when not playing a record and the turntable was idle. In other words, the noise level was much higher when the input selector on the P5 was set to phono vs. other inputs.  Later, I upgraded to the Parasound P6 preamp. I noticed the same hiss, when the volume was turned up. I just assumed it was the turntable, since the problem (albeit minor) happened with both preamps.

As some of you may recall from a recent posting, I just purchased a new turntable. Yesterday, I received it - my new Rega P8 turntable with factory installed Alpheta2 moving coil cartridge. The hiss is worse!! So now I have experienced this background hiss with two different preamps and turntables. is this normal?  I'm wondering if the higher gain needed for the moving coil cartridge is adding to the noise level.  Could I be expecting too much out of the phono preamp section of the P6?

Note that both the turntable and amps have power run through an Audioquest Niagara 1200 line filter, so I do not think it is AC noise.  But the noise level is much higher on "phono" compared with other inputs.  Do any of you all notice this with your equipment?