Background noise

Background noise is normal with tube gear.

Your definition of "fairly high level" of background noise could be skewed by your experience with SS.

Or, you could have a problem.

It's hard to judge based on your description.

Sounds normal but I agree with Tvad, hard to tell based solely on info given. Do you notice any difference between other inputs and Phono or is it all the same result?

there is no noise I can hear from the other inputs, even at maximum volume levels. Just to give you a better sense of the loudness of the noise, I just set it at the maximum level, stepped out of my listening room, moved to another room that is approximately 8 meters away from the listening room, and could still hear it.

BTW, I bought the Monbrison 3 months ago from someone who bought it in October. Called Shindo and they told me that the warranty is not transferable...weird policy for a luxury product, if you care about keeping your customers. That said, the Monbrison is just wonderful

Do you listen with the volme at maximum level?

I have never owned a preamp (SS or tube) that was dead quiet with the volume control turned up even three quarters of the way.

Perhaps the phono gain is set too high for your particular cartridge. Perhaps you have a pair of noisy phono section tubes. Perhaps the noise you're hearing is normal for the unit. It's hard to say.

I owned a highly regarded preamp with phono (retailed for over $15,000), and it was fairly noisy without music playing, but the noise was not apparent during playback. Even the manufacturer admitted his phono section has some normal tube noise.

My guess is that what you're hearing is normal, but you might swap in another pair of tubes in the phono section (a pair you know to be "quiet"), and you may look into the gain setting (if this is adjustable on your preamp...).