I built my Stereomour as a 2A3, then I modified it to the 45. In terms of comparison, I find the 45 to be more "subtle" in the sense that when you listen to jazz or vocals, you can hear all the different instruments more clearly than the 2A3. Of course, you will need a suitably pair of speakers with sufficient sensitivity. I am currently using a pair of Tekton Lore - 98 db which are very easy to drive. The choice of music also matters. The 45 is in my view ideal for jazz. I have found that for full orchestra classical music, both the 2A3 and the 45 and even the 300B is not sufficient, ( I owned a 300B/2A3 amp and I preferred the 2A3 to the 300B), and sometimes I revert back to a push-pull amp for this musical genre. Perhaps a quality sub will help in such a case to get to sub-bass sounds of a full orchestra. I recently replaced the 45 tubes ( GEs) with JJ 2A3s with the Stereomour in the 45 configuration. While the JJ 2A3s were louder, I preferred the 45 and switched back after a few days. Hope this helps.