I'd second the tube rolling option to potentially improve your system.
I have no experience with a SCHIIT FREYA +, but did recently do some tube rolling in my Pathos Classic One MkIII with amazing results. I had a less than ideal setup before (still sounded great), but replacing them with a quality set of vintage Mullards the improvement was enough to almost seem like I got a new amplifier. I have two more sets of the tubes on the way to hold onto for the future. Another Pathos owner recommended and sold the tubes to me. By far the best $90 I've spent on audio equipment.
You should be able to find someone that's rolled some tubes in your premaplifier and can point you in the right direction.