Amplifier for Pioneer SP-BS41-LR

If you are fine with the form factor of the AMP-100, i would also consider classic/vintage stereo receivers in places like Craiglist, etc? DTA-100A is great but always out of stock so another option if u want small

http://www.houseofdap.com/topping-tp22-t-amp-tk2050-tc2000-tp2050-digital-amplifier.html

I've known peeps driving 4-6 ohms speakers fine with T-Amps ^^

Same boat as you, OP! For what it's worth, the Pioneer speakers sound bloody amazing in my living room setup (when they get a chance to flex their muscles -- they're being used as rears). Gonna play close attention to this threat to see what y'all decide on.

What will you be using the speakers for?  Music only, or will you be doing some gaming or movie watching as well?

If you WILL be doing movies or gaming, an A/V Receiver might be your best, most cost effective option.  You can get virtual surround processing from the A/V Receiver, and in the future when you move to an apt or house, you could use your A/V receiver for a full out surround receiver. 

If you don't currently have a soundcard that will provide a simulated (or "virtual") surround, I really think a good A/V receiver would be an excellent way to go. 

Which, does make me ask....what is your source?  I'm going to assume computer since you're posting in the Computer Audio section, but let me know if I'm wrong.  What outputs does your computer currently have?  Laptop or desktop?

Then I agree with the other poster. Your best bet is probably Craiglist. Or you can pick up a factory refurbished/factory warrantied Onkyo from accessories4less.com.

However, does your laptop have optical or HDMI out? If so, then an AV receiver instead of 2 channel is probably your best best. Laptop onboard audio is generally not that great, and the DAC built into an AV receiver should give you better sound. Also, if you ever decided to get a sub, the bass management features on an AV receiver make sub integration easier. 

Those Pioneers are nice speakers for the price 

Believe it or not, this Lepai t-amp works surprisingly well. Here it is on Parts Express, too. Save the rest of your money until you can find something better than the Dayton, which is not significantly better (it's a t-amp too). I had one that I bought to try it out, but gave it away to a friend who needed an amp and he was delighted by how well it worked. It won't bust your ear drums, but it gets reasonably loud and sounds good if you keep the volume at 12 o'clock and lower.