I may be one of the few people that has owned a U70, an SET 120, and now a DV225. In all cases I cannot comment on the bass response since I have a pair of VMPS subwoofers and have always used these amps with a high pass crossover, in the last case crossed over at 250 hz.
I really loved the U70. The midrange was very creamy and dimensional. Top end very smooth. I had it matched up with a pair of Infinity IM4.1, each speaker had a powered subwoofer driven by 850 watts. Perfect match.
Then I bought a pair of Raidho C1.2 on auction, that I really didn't intend to win. The U70 choked big time on this load. I bought an Odyssey Kismit in Khartago Case which drove the Raidhos well enough, but I never took a shine to the Raidhos. They just didn't sound very good to me, at all. I really prize dimensionality. There just wasn't anything there.
I traded in the U70 on an SET120. I forget why.
I found the sound of the SET120 to be quite similar, with the same midrange creaminess but the transients and microdynamics seemed a bit quicker and more incisive. I really like the SET120 and found it had plenty of power, when crossed over at 120 hz, or higher.
I then lucked into a pair of New Old Stock VMPS RM30's with an external crossover. Really quite remarkable speakers and can do the full disappear act, and the planar panels cross over at 280 or so, revealing a lot of things buried down there. I have them set up a little bit differently. I have a Marantz AV8802A pre-pro and the pair of VMPS subs are powered by Bash plate amps. The plate amps also have a high pass crossover, I take the pair of sub outs from the Marantz and run them to the plate amps. The high pass from the plate amps go to two channels of an Adcom 5 channel amp (125 watts a channel) and from there to the woofers on the RM30. The SET 120 then was set using the crossovers in Audessy set a 250hz. The SET just sees from 250 hz on up, driving just the neopanels and ribbon tweeter. The VMPS 6 inch woofers see from 100 hz (or so) from the plate amp crossover to 250 hz (the Marantz crossover) and the subs are driven from 20hz on up to 100 hz.
The SET 120 really shines in this set-up.
However, Frank came out with the DV225, and I would need to send my SET 120 to get a speaker binding post repaired (it had come a little loose). I figured what the heck, Frank gave me a nice trade in on the SET120 and I got the DV225. In my set up I have no need for the power, but I look at the DV225 as a 20 watt Class A amp, with a lot of headroom.
The SET puts out a nice soundstage and it very dimensional but the DV225 is most definitely the soundstage King. I see deeper into the soundstage than ever before, and much wider as well. Super happy. Somebody above commented that they liked the midrange of the SET120 better than the DV225, I have to disagree. The DV225 is everything the SET120 is, and more.
it's kind of crazy how compact and cool the DV225s run.
In my opinion the SET120 control amp should be all that you need and more, and you will be hard pressed to find something so musical at even twice the price (which means you can do better with a new one than with a used something else.) It fits easily within your budget, and allows for investment in equipment in other areas which will lead to a more enjoyable system.
Good luck in your quest!