I'll offer an alternative suggestion, if you don't mind.
Dan Wright has a new tube rectified PSU for the SWL that adds a very sweet warmth that the original PSU lacks.
From what I heard at RMAF the new PSU and the other changes Dan has made to his preamp changed the SWL from a non tube sound to a more musical tube sound while maintaining the SWLs dynamics and deep bass.
I plan on having my SWLs PSU swapped as soon as I can part with it.
This and a tube swap might add all the warmth you are looking for.
Dan Wright has a new tube rectified PSU for the SWL that adds a very sweet warmth that the original PSU lacks.
From what I heard at RMAF the new PSU and the other changes Dan has made to his preamp changed the SWL from a non tube sound to a more musical tube sound while maintaining the SWLs dynamics and deep bass.
I plan on having my SWLs PSU swapped as soon as I can part with it.
This and a tube swap might add all the warmth you are looking for.