Thank you for all of the replies. I was afraid of the answers I was going to get.
Let me say that I did hear a difference between the 2 VT100s and the REF150 but it wasn't as large as expected. The bass was tighter and the treble was more extended (as extended as SL3s can be while being driven by a tube amp with a relatively high output impedance
). All instruments and voices were clearer but again not a night and day difference.
The amp was advertised as having low hours - 750 hours but when I received it it had double that. I will be re-tubing it when it gets close to 2000 hours. I was thinking of getting ARC supplied tubes unless people here have other opinions.
So basically, I should be looking for a REF 3 or REF 5se to replace the LS25.
I wonder if the LS25 was also holding back the Pass Labs X350.5 that I tried before returning it and searching for a REF150. I did not like the sound of the Pass Labs at all. I found the bass just drowned out everything else. Of course, my panels were really old (20 years old). I just replaced them. Still I like the sound of an ARC tube amp more than the Pass Labs. I know that this is contrary to what many people seem to say when pairing Pass Labs amps with Martin Logans but that is my opinion.