I absolutely agree with MarktheNut's recommendations for the 6SN7-based tubes amps by Don Sachs or Supratek. I had Don Sachs original tube preamp and now have his newest version and it is fantastic. I suspect the Supratek is quite fine too. Quicksilver makes great tube preamps, as well. The Schiit Freya, with upgrade tubes, might give you a glimpse of the SQ of the Sachs preamp at far less cost.
I personally think that there is magic in 6SN7 tubes in preamps. The new best Chinese 6sn7 tubes are outstanding, rendering my stash of dozens of vintage NOS 6sn7 tubes merely "closet queens."
I personally think that there is magic in 6SN7 tubes in preamps. The new best Chinese 6sn7 tubes are outstanding, rendering my stash of dozens of vintage NOS 6sn7 tubes merely "closet queens."