Phono stage gain setting to match preamp and power amp capabilities

Hello All,  I have a Whest PS .30R phono stage, with adjustable gain settings.  My Audio Research LS-25 preamplifier also has adjustable gain settings (high 18db, medium 12db, low 6db; I have been using high at all times as I believe this is the best sound quality & "native" setting).  The Whest gain options are 43, 50, 55, 60, 65, 72.  It also has adjustable load settings of 100, 220, 470, 1k6, 15k, 47k.

The cartridge is Lyra Delos (Output voltage: 0.6mV@5cm/sec.) The power amp is an Audio Research VT100 (100wpc).  The speakers are Rockport Mira Monitors ( somewhat low sensitivity at 85 dB SPL/2.83 v)

The reason I am looking for advice here has to do with how much I have to turn up the volume control on the preamp up to get to the loud volume that I like to listen at when I am in my loud listening moods.  In order to get to the point of a dramatic concert style experience in my living room, when playing vinyl, I have to turn the preamp volume to the 3 o'clock position. Once I get the volume control this high, the noise floor (am I using the term correctly?) or background hiss increases audibly.  I do not get loud volume without that hiss.  Of course, when the music is full, you cannot hear it.  But when the music is lean, the hiss is there.

For the past year or so, I had the Whest set to 60db and 220 ohms.  I arrived at 60 because I didn't want to over amplify the signal in the phono stage and get more hiss.  But then I had to crank up the preamp volume.  Now I just set the Whest to 65, and as expected, the volume control on the LS-25 can be backed down a little.  I haven't had the chance to really listen critically or for long enough time to determine if the hiss has diminished.  But I will log the listening time soon.

Can you give me any advice on the proper way to set these options?  Should I go to full gain on the Whest and back down on the LS-25 volume control even further?  Or is a lower gain on the Whest a better way to go?  Also, can you help me understand the nature and source of the hiss I hear?  What is it, why is it there, and how do I get it to be 'inky black' as some reviewers like to say?

Thanks!
Mark