Absolutely agree with unleash 100%.
I use a 2 channel amp for movies and do not even use a sub. I have two amps, one SS and one tube amp. Usually use the tube amp for movies like Amadeus, Sound of Music, My Fair Lady or Jodha Akbar and use the SS one for movies with more thumping sound like The Dark Night, Casino Royal etc (because don't want to strain the tube amp for those purposes, don't need it for that kind of sound anyway).
My DVDP does video upscaling to 1080p (when connected to my Bravia TV with a good quality HDMI cable). At the same time 5.1 channel audio can be downmixed to 2 channel PCM. I take the digital audio out through a coaxial cable and put it in a DAC. Analog outs from the DAC then goes into the 2-channel amp. Alternatively, for a high quality DVDP with a better audio DAC part, one can also take the 2-channel analog audio out directly from the DVDP and put them into the amp.
You will not get the surround sound (although some DVDPs while downmixing gives an option for simulated surround, but not sure if it really makes a difference), but you will never miss the centre channel. A very good pair of speakers plus a reasonable amp create the effective centre channel anyway. If the speakers go down to the bottom frequencies, you may not miss a sub either, although the requirement of bass like anything else is highly subjective.
I do not have a blue-ray player, but my guess would be that it probably also does the same kind of job with respect to the upscaling and downmixing and all that.
BTW when one sends AV signal through HDMI to the TV, one needs to adjust the TV volume to zero manually (my DVDP does not have the option of setting HDMI audio off, but some players do have that option) otherwise TV speakers will act as actual centre channel, but TV speakers should be off because they are usually heavily compromised when compared with 2 good quality speakers as used in a stereo system.