Need to steer away from Bryston amp added to AVR

I have a hamburger budget, but want kobe beef. Need a new menu....

I am researching amps to find the best solution (sound/budget/aesthetics) to add a amp to my very decent denon receiver to improve the sonics for stereo (2.1) music only. I am not expecting the "ultimate"sound just want to have a noticeable improvement in sound. My budget is $700-$850 - Yes, used is fine!! No tubes please.

My current set up, in a 14 x 19 x 8ft living room:
.primary source: G5 Powermac music server - AIFFs via TOSlink
.denon dvd-1730 for CDs occasionally
.denon avr-4306 receiver @ 130W (I will use pre-outs for 2-channnel)
.tetra 120u monitor speakers (8 ohms, 89dB, 50-20k Hz, bass-reflex)
.martin logan abyss subwoofer
.anti-cable speaker cables

Music varies: bjork, stevie wonder, depeche mode, ladytron, the faint, the smiths, ry cooder, gotan project, cowboy junkies, interpol....
medium listening level.

On my current list are a bunch of amps that are 2 - 4 times my budget:

.Bryston model :: 3B SST, 150W, SS ~$3000 MSRP
.Audio Research :: model: 150.2, 150W , Class-T, ~$3000 MSRP
.Bel Canto :: model: S300 (current model), 150W, Class-T ~$1650 MSRP /
model: EVo 200.2 (previous model) 120W, Class ? ~$2200? MSRP

Q: Would something like this parasound amp be a marked improvement over the Denon's internal amp?

.Parasound :: Model 2125, 125W, Class AB ~$700 MSRP

The BIG Q: Which amps should I be looking at instead of these $$$$ listed.

Thanks for any leads you can provide, ed
At that price, a used McCormack DNA 0.5 or 1.0 would be a good way to go. The 0.5 at the lower end, the 1.0 at the higher. But you will run up against the limitations in the internal pre-amp pretty quickly.
Thank you for the amp suggestion. Yes, I do realize that my dual purpose system will never reach audio can't convert an suv into a roadster. the denon does have a unique mode that shuts down all the non-audio circuits, etc. during audio playback. I use this mode 99% of the time.
If you are looking at the Parasound 2125, take a look at the Parasound Halo A23. A great sounding amp, that is kind of middle of the road. Can be had for around $525.
want to have a noticeable improvement in sound.

Given the relatively modest size of your main speakers I think you have a great and well balanced set up with your Denon @130 W per channel. I don't believe you can achieve a noticeable difference given your medium listening level requirements. I assume your sub is taking most of the tough LF load away from your main speakers anyway. (100 watts is plenty for all but the very lowest frequencies, as it is the woofer that takes all the juice; your sub has a built in amp so no worries!!!)

Have you considered acoustic treatments? Do you have a PEQ to control the LF room modes (less than 8 HZ)? These options might give you a noticeable improvement.
I agree with Shadorne. It looks like you are using the Denon receiver's DACs/analog section. That might have a bigger impact that the amplification. You might consider a 2-channel DAC in front of the reciever so it is only used as a volume control.
I second the McCormack DNA 0.5. You might even be able to get DNA 0.5 Deluxe in that price range. Good luck.
I have to agree with Shadorne, swapping in another amp isn't going to do much towards improving the sound. You'd be much better off treating the room or getting better speakers. Treating the room is much less expensive, but getting new speakers is always a treat...

Thanks for the input all! It is great to see differing philosophies. Many will often just dismiss denon altogether. Thank you for not taking that tack. Which is sort of what got me in the spot to start with....many comments online about the "garbage sound" that comes out of mid-fi AVRs.

Yes, I am considering room treatments. but they need to be aesthetically agreeable - to ME. No, I don't have a WAF, but I do have extremely critical aesthetic criteria...I work as a designer. And honestly, I am just picky. I really like the auralex spacearray, but am trying to figure if I can DIY for less $$.

I want to stick with my current speakers for now. Regarding the parametric EQ, I hear what you are saying and get the basics of nodes, though I have no experience in this area -guess I need to read up. thanks again.

Additional comments welcome.
Why not try a pro amp such as Behringer? Lots of people like them. Some day they are junk. At the asking price worth a try.
Have you considered an integrated amp? Unless you are using the Denon other than two channel, maybe you can get something for it and raise your budget alittle bit for let say a Plinius, Ayre or Classe integrated.
kayoboy, I guess I could have been clearer in my orig post. I only listed my setup above that relates to 2.1 audio playback. this system is also a 5.1 HTvideo set up -I just left off the other equip. My last music set up included an integrated, I am a fan.
I was only echoing Swampwalker's post that the internal preamp of the receiver could limit whatever improvement any amp you get. By the way there is a Classe integrated listed for $900 that might fit your needs and still use the receiver for 5.1