Help in minimizing hiss

Since you already have  warm sounding Pass amp why not try the noiseless Benchmark LA4 preamp, 30 day free trial and $2500. 

https://benchmarkmedia.com/collections/preamplifiers

I doubt that new tubes will help, but give it a try. You can do much better than the Freya but you will most likely have to spend more money. In my experience your cables will not help this problem one bit.

You should work with a reputable dealer and request low-noise and low microphonic matched tubes. The quality and noise level of a 6SN7 can vary greatly, but the right tube will provide wonderful sonics in a preamp.

I mentioned a power conditioner for your sources since noise from the AC line will also be audible thru your speakers. This is not hiss, but every line connected to the power grid will introduce noise into the system (even a dedicated line). 

@erik_squires  I do have absorptive panels covering much of the wall behind the speakers and a 2'X4' treatment on sidewalls at first reflection points. Room is 18'X 34' with 19' ceilings.
@jsautter I'm only rolling tubes to replace the JJs that came with the Freya.
@lowrider57  Tube Depot set me up with low microphonic, matched etc GE 6SN7 GTAs. Should be here in a few days.