The experience with my LS-25 was a much more detailed mids, the same amount of treble but more beautiful and more delicately presented, more air and space in the music; mid bass is more defined, more holographic, male singers came to life; Lowest octaves of bass appear to be more powerful.
In general, the tubes are much easier to listen to than the stockers.... The thing I liked the most was it took a harsh edge and some siblance off of my treble, and the harmonics were better. Don't use the ARC tube rings with the 6H23 (NOS Sovtek 6922 from upscale). I also did my VT-100 -- More of the same good for the sound, not recommended if you do not know how to do the VT-100 complete alignment procedure. E-Mail me for more detail on the alignment procedure. I can't give you the procedure, but I can tell you how to get it and what it entails.