What is Moving From Solid State to Quicksilver Mid Monos Like?

@fastcat95 ..." Can anyone out there who has made a move from good SS equipment

to the mid monos tell me what they gained that made them happier with the sound?"...

Some of what you might "gain" or even "miss" may also have a direct dependency on your speakers impedance, efficiency, and the size of the room too.

+1 to what @oddiofyl stated. If you can swing it, plan to keep both for a while and rotate back and forth. You’ll end up appreciating both for different reasons.

While I have the larger QS monos running KT120s now, and not EL34s, and also still alternate with 50w Class A SS amplification [formerly 200wpc SS] - both have their +/-. I suspect the "midrange" is what you’ll probably like most about the QS Mid Monos. I helped a friend into getting a pair of mid monos after he heard my other EL34 amps of the past. He talks about getting more efficient speakers now from time to time, but it’s not totally necessary. His prior amp was EL34 tube based and 2x the power of the mid monos. The mid monos came into the picture for more reliability. He now has a large subwoofer to go along with his QS Mid Monos. Fills the room now with more low-end reinforcement. It is  a larger than average room with really high ceilings.

Imo, the top end and lower end bass drive will still be there if your speakers are more on the efficient side. I’m keeping in mind you are coming from a DNA 125. When I use to flip back to my former/larger SS amp with more power [like your DNA 125], there was this added sound pressure that filled the room a tad more in a larger room with less efficient speakers. Again, the room and speakers matter here too. This is what might also be considered about what you might "gain" or "miss" or be happy with. Try both, keep both, and rotate. Best of luck.

@yogiboy which 83db speakers were you using with Mid-Monos?  Are they 4 or 8ohm?

At my 55year-in-business local dealer who sells AudioNote and Quicksilver, I've also heard low power 10w amps playing 83db speakers there which are 8-ohm. Sure the amps power the speakers to play sound, yet the dynamics, volume level and room filing sound capability was a bit constrained. 

Good to know @yogiboy and thanks for responding.  I'm thinking most of Mike's QS amps seem to respond and sound, dare I say, more musical with higher impedance speakers, 8ohm and above.  

@fastcat95 "...(.75" tweeter, and dual V.C. 6.5" bass mids). 89 dB sensitivity; impedance probably drops to 4-6 ohms" "...what do you think???"

My friend has a similar speaker configuration and spec, slightly more sensitive than yours, similar impedance - running with his QS Mid-Monos. His former high power amp w/EL34s drove his speakers a little better, more bottom end. It’s fine for low volume, but when he needs to turn it up a little more - having the separate/extra subwoofer helps quite a bit. As noted before, he is back to looking for more efficient speakers in order to keep the Mid Mono amps instead.

If you truly want a more comparable step-up move with tubes coming from your DNA 125, keeping your existing speakers, I’d say skip the lovely lower power QS Mid-Monos and go with the newer KT Monos -or- one of the prior generation amps in the 60-90w range. For ref - several prior products are listed here to keep an eye out for used market fwiw. Others here might chime in too. I think at least the former Mono 60s or Mono 80s would do the trick I’d bet. They pop up 2nd hand periodically https://quicksilveraudio.com/past-products/

If you run the tubes the amps and circuit was designed to run with day-1, and you keep an eye on the bias, turn them off/on properly in sequence - some people will argue good tube amp(s) will last longer, and can be lower cost to repair - if they ever need repairs.  Particularly when there are no aging and cracking circuit boards inside. While I own and use both, replacement parts are easier to find for my tube amps than my Class A solid state amps as learned over time. Choose well!