Amp for Various DIY Speakers

I am looking for an amp to get started on my my 2 channel setup. I will be running various DIY speakers through it (currently Paul Carmody Tarkus, but looking to build Zaph ZRTs) so I am thinking something that can easily go down to 4 ohms is required. So far I have looked at the Parasound A23 and the NAD C272, both used off of E-Bay or Audiogon. I also might consider a pair of Outlaw 2200s or Emotive UPA-1s, or maybe the XPA-2 or XPA-3. However, those options are all slightly above what I was hoping to spend so I would probably try to wait for a sale. Other than having some guts and ability to drive a wide variety of speakers I am hoping to get something with balanced inputs and good performance in general. Aesthetics are also important since I think this system may end up in our bedroom. I have read good things about Emotiva, but for some reason their designs just don't do it for me. I am still certainly open to Emotiva though if they are a much better value than anything else I am looking at. I have a NAD 7 channel amp that has served me well, but I read about overheating issues with the C272 which made me shy away from that. For some reason I am really drawn to the Outlaw 2200s or the Parasound A23, but I don't know why. I am also hesitant to spend too much on a used amp for fear that it will die after a short time and won't be under warranty.

Upstream of the amp, I will just be using the pre-outs of an old receiver I have initially. Once I get the amp purchase out of the way, my next purchase will be a preamp, and then on to quality source components. So, what amp would you all recommend, either from the above list or outside of it, for a wanna-be audiophile? I am hoping to stay below $500, but could bump that up just a bit if an incredible deal came along.

Thanks,

Matt