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