Welcome to the forum!

I can help with this. My Decware journey started in 2020 with a pair of UFOs with the “anniversary mods” which at the time were upgraded signal and power supply bypass caps. And long story short they were so good I got back on the waiting list for a pair of UFO25s that I received last November. I will say without hesitation or qualification I am very happy with the UFO25s and the best way I can describe the difference is to say it is just more of what makes the UFO so good. More transparency, more detail, more dynamics, bigger sound stage. The “sound” of the amp, and the frequency response are pretty similar between the two, but more on that below. FYI/FWIW you can see my system in my sig.

I’m guessing what you’re really after is whether the 25 is worth the money vs the UFO. There are at least a few other posters who have upgraded and I’m pretty sure none of them have regretted it. But I will say this, if money is an issue the UFO with the mods gets you pretty close to the UFO25, esp. if you are not interested in tube rolling. If you plan on exploring tubes, both amps are a playground, but the extra transparency plus VR tubes in the 25 gives you options to tune the sound way beyond what’s possible with the UFO. Of course this can be a double edged sword because it has made me a little crazy at times trying to get everything just right. But, if you see yourself sticking with the Decware tubes, which sound great, you might find the cost difference better spent upgrading e.g. cables or power conditioning or your front end. Of course if you have the budget for a UFO25 then see above for unhesitating, unqualified recommendation.

You asked for songs and I’m not going to do that, because what I said earlier applies to everything to which I listen. I listen to a lot of classical, more orchestras than chamber or solo instrumental. I listen to some jazz, mostly golden age stuff:Stan Getz, Bill Evan’s, Rollins, Miles, those kinds of cats and also big bands. And I mix in a little classic rock as well. My UFOs played it all great. The UFO25s play it even greater.

I hope this helps, I’d be happy to discuss further but I’m heading out of town and off the grid for a couple weeks so if you have questions or comments I’ll respond when I get home.

On an earlier forum, someone described the difference between the two and it remained (paraphrased) in my head. It was described as such: With the UFO, every so often you have those WOW moments. With the 25th, those moments happen much more often. It is a simple but apt description.

Having upgraded myself, although I have not listened to the UFO in several years, there is another level of refinement in the sound, perhaps somewhat attributed to the VR tubes in the 25th amp. There is a darker background due to the lowering of noise and that allows greater detail to come through. I've never regretted upgrading to the 25th anniversary and I've yet to reach the bottom of this musical rabbit hole. It is possible it might be the most transparent tube amp out there.