Which is better, gain in phono stage or pre amp?

I have a Shelter 501 MC cartridge into a Plinius M14 solid state phono stage and a Lamm LL2 tube pre amp. The phono stage has adjustable gain on the front panel so I can easily adjust between high and low. The Shelter is a moderate gain MC (.4MV) so I have been using high gain but this only allows me to adjust the volume on the pre amp up 1/4 turn for reasonably loud levels. If I use the low gain on the phono stage I get a notch or two more range in the pre amp volume adjustment which is nice but is it better to amplify the signal from the cartridge through the step up transformer of the Plinius or by pass this and use the gain in the pre amp? My own listening suggests minimal difference but I am interested in a technical explanation of the difference of phono stage gain vs pre amp (I'm not an electrical engineer).
(If it makes any difference, my amp is a Plinius SA102 and my speakers are B&W Nautilus 803 which are fairly sensitive at 90Dbw)