First of all, the LS 15 is very much in the analytical zone of ARC line stages. The LS5 and LS25 in any variations would be a huge step in the right direction in the context of 3-dimensionality and harmonic richness. There was no brightness nor fatigue with the LS15, I simply found it uninvolving.
When I was looking to upgrade from the LS5 II and then later Mk III (7 years for these), I gave serious consideration to the LS25 II. The added cost to go to the LS25 made no sense. There was a little more detail hiding in the background, but it was also not as involving. I could not attribute this to the 6H30 tube as the BAT 31SE, which also uses this tube, had the LS5's dimensionality strengths but also had greatr tonal coherency than the LS5. I confirmed this at my home and at the BAT dealer. I ran with the 31SE for 2 years until I heard the Aesthetix Callisto Sig.
I had a quad of Sovtek 6H30 and the original 6H30 tubes from BAT. There was a bit of a difference and improvment with the BAT tubes, but not at all earth shattering.....not at all in the way various Telefunken, Mullard, Amperex, etc., 6922 tubes destroy the Sovtek.
The only way to answer your questions on analytical, clinical, lifeless, etc., is to try any of these in your system, directly to the LS15, and hear for yourself. There are so many line stages on the used market in the $2000-3000 range, with the Aesthetix Calypso and Lamm L1 at just a little more.
Try not to get too wrapped up in whether or not a product in this price range is 6H30 based or not. There are enough compromises in each of these models to make the type of tubes used a rather moot issue.
When I was looking to upgrade from the LS5 II and then later Mk III (7 years for these), I gave serious consideration to the LS25 II. The added cost to go to the LS25 made no sense. There was a little more detail hiding in the background, but it was also not as involving. I could not attribute this to the 6H30 tube as the BAT 31SE, which also uses this tube, had the LS5's dimensionality strengths but also had greatr tonal coherency than the LS5. I confirmed this at my home and at the BAT dealer. I ran with the 31SE for 2 years until I heard the Aesthetix Callisto Sig.
I had a quad of Sovtek 6H30 and the original 6H30 tubes from BAT. There was a bit of a difference and improvment with the BAT tubes, but not at all earth shattering.....not at all in the way various Telefunken, Mullard, Amperex, etc., 6922 tubes destroy the Sovtek.
The only way to answer your questions on analytical, clinical, lifeless, etc., is to try any of these in your system, directly to the LS15, and hear for yourself. There are so many line stages on the used market in the $2000-3000 range, with the Aesthetix Calypso and Lamm L1 at just a little more.
Try not to get too wrapped up in whether or not a product in this price range is 6H30 based or not. There are enough compromises in each of these models to make the type of tubes used a rather moot issue.