Personally, I found the Acurus quite harsh. The other choices won't be louder but quantity isn't everything.
I had an Acurus A250 paired with a Melos preamp, and the sound was very nice. Swapped the Acurus on a Sonographe A400. Still have that and the Melos. I was using Paradigm Reference 100's for speakers. I heard a Parasound solid state amp and preamp with those speakers, and thought the sound was extremely harsh. Made me think all SS amps should be preceeded by tubes. Did not like the Parasound over the Acurus, but should also add this was 10 years ago, before the new Parasound amps. I heard a B&K amp and a Denon digital preamp through some Vandersteen 2ce's back then and liked the sound a lot. The B&K St-102 amp, I believe. When I bought my A250, it was half the price of the Aragon 4004, and I was advised the Acurus was too close to the sound of the Aragon to justify the extra money. I liked the Acurus, got bit by the upgrade bug, liked the Sonographe, which was half of retail, and half of that was taken care of by the Acurus trade. Hope this helps.
I've owned many Parasound and B&K amps. The only Acurus component I ever owned was an ActI which I liked a lot, except for the fact you needed it to be connected to a monitor in order to tell what mode it was in.
As for amps, I've owned many of the "Ref" series of B&K, and the "HCA" series of Parasound. I had like both and found the Parasound to be somewhat "bassier". The B&K's seem much more neutral. Ultimately I like the B&K better for this reason, though I do wish I still had my Parasound HCA2200 - it's a n excellent and bulletproof high current amp. I still have B&K M200 Sonatas which are about the best amp you can find for the money (or twice the money for that matter).
Finally, my impression is that Acurus equipment is on the same class as B&K and Parasound. If you like your amp, no reason to jump to another brand. OTOH, I've read that Acurus amps are brite, which can't be said about either B&K or Parasound, and some models of B&K are very warm sounding (especially the M200 Sonatas). If you find your sound too brite, B&K would probably cure this.
I agree with Bdgregory's evaluation of the B&K M200 sonata monoblocks as I also had a pair driving merlin 4b+'s and dunlavy scIII's;excellant results with a tube like sound.
These amps were bullet proof and do show up here on audiogon now and then.
I have no experience with the other 2 models in the thread.
Thank you everyone. Great information so far.
Bdgregory: I can attest that the Acurus is NOT a bright amp at all. If anything it might need to be a little more open in the highs, but thats just my experience with my decent/ok equipment. Bryston was quite bright and felt thin in my opinion. Nice punch but not something i'd listen to all day.
So if a person was to upgrade, what 'hi-fi' brand will sound warm and detailed without breaking the bank? I'm going to avoid Bryston.
I don't know about the other brands, but I bought a used B&K 200.2 a few months ago and I love it. I switched from Carver and the B&K is a much more nuetral sound. I'm driving Paradigm Studio 40's which tend to be bright and this helped calm them down. I got it for $650.00 and have seen them going for less than that on here.
Having a Acurus amp for some years, I find it quite good and on more neutral than anything. It lets your music come through as it came in. I also have a small zamp 3 amp from parasound. Connected to my VSA jr4's. they reveal perhaps a little more clarity in the details of some recordings. Just to try something different a would consider a more powerful Parasound amp. I am just as impressed with it as the Acurus. Would check out the Odyssey as Reff suggested if it would be in your price range. Overall, I feel you would get more bang from your buck by changing source gear or speakers. Good hunting, it is half the fun.
I have directly compared Parasound (HCA2205at - which I still have), and the B&K Reference 200 and MCA (I think) versions. I am driving NHT 2.9's which are very current hungry, and the Parasound was a better match. Better bass extension and control, but also a bit boomier, if you are not carefull with your speaker placement. I also agree the B&K had a very neutral sound, but it was just too laid back for my taste. After living with both for over a month, I kept the Parasound.
Hope this helps!