It is impossible for me to know, via a written forum, how much "hiss" you are hearing.  It is "normal" for there to be some hiss present in your amp.  But how much is too much?  That is hard to determine with just words.  As volume increases, any hiss that is present will also increase.  Treble and Presence may add to your amount of hiss.  Tubes are always a suspect in a tube amp.  Try new pre-amp tubes one at a time , staring with V1.  If you do not have any spares you need to buy some immediately.  In the mean time try swapping tubes.  Remove the tubes from V1 and V2, reinsert them in there opposing tube socket.  Install V1 in the V2 socket and install V2 in the V1 socket.
Try that for starters and tell us what happens.  Post some pictures if you have a chance.  Did you build the amp by yourself?
Good Luck

Who's chassis and board is this, not from Ceriatone is it?
It is hard to tell from the photo, but it looks like the Neutral is fused.  Am I seeing that correctly?
On V1 you could try reversing the orientation of that chubby, Sozo, 0.68mf so that the foil side (the side of the cap with the line) is toward the front panel.
I have a few other ideas, but lets wait and see what the tube swapping does.
Nice clean build by the way. Looks like you did a nice job!!