Question on phono input noise levels

At normal volumes you should hear nothing. If you turn the volume up all the way you will hear some noise and it to try to play it at that volume you'll either blow an amp or break a loudspeaker. If you hear it at normal volumes then you have a noise source near your turntable. You have a lot of gain and can amplify almost anything. Don't take anything for granted. Unplug everything but the turntable, preamp and amplifier even the line conditioner and see what you have. Change the position of the turntable and see of the noise changes. If the noise disappears plug in one unit at a time and see which unit is causing the noise. Don't forget to make sure all your gain and load settings are correct for that cartridge.

Good Luck,
Mike

Noise is proportional to gain. 

That is, the more a signal has to be amplified, the more noise you are going to get as a result.

Of all the audio signals a preamp receives, the input from a moving needle is the smallest, so this effect is typical.

Something tells me that’s probably not true. 🤔

“At a nice satisfying volume I can hear the exact same sound you describe- from the door 20 feet away. Easily“

That is not normal at all. 

The Parasound P5 and P6 have gains that are somewhat low for use with a cartridge such as your Apheta 2, which is rated at 0.35 mv. Both preamps have specified phono input "sensitivities" of 52 db, with the line stage of each preamp providing an additional 10 db of gain. And Stereophile measured the gain of the phono section of the P5 as being 53.9 db.

In addition, generally speaking I would not expect a full-function 2.1 channel preamp + DAC + headphone amp costing $1495 to provide particularly good noise performance in its built-in phono stage.

Also, FWIW, I use a Herron VTPH-2 (not 2A) in conjunction with an AT-ART9 LOMC cartridge rated at 0.5 mv, with the Herron’s stock tubes. If I turn the volume control in my system to a setting slightly higher than I would ever use (which is quite loud; some classical symphonic recordings I listen to can produce 105 db peaks at my 12 foot listening distance) the hiss produced by the phono stage is only audible within about 1 foot of the speakers. The Herron (which is only a phono stage, not a line stage or preamp) provides 64 db of gain and lists for $3650.

In addition to the SUT approach that was mentioned, a number of separate phono stages are available which cost considerably less than the Herron and have received a lot of favorable commentary here and elsewhere. The Gold Note PH-10 being one example. I believe that using a quality external phono stage connected to a line-level input of your P6 would considerably improve both the hiss and the sonics that you experience when playing records.

Good luck. Regards,
-- Al