@stlyde,
Congratulations on your recent purchase. You made a great decision to go with Ref6 over GSPre. My dealer told me that GSPre performance rivals the LS28. The REF6 is a definitive upgrade over GSPre or LS28. I went from LS28 / VT80 combo to REF6 / GS150.
Once you’re settled with the new combo, I highly recommend to upgrade the stock Sovtek 6550WE Tube to SED 6550C Svetlana -C- / Russia Tube. This upgrade yielded tighter bass and more meat to the bones to overall soundstage.
To my ears, 6550WE Tube had bass less defined and fat, YMMV.