As others have said, if you know you are only going to listen to stereo CDs, for now and in the future, then getting a good stereo amp (or maybe receiver) makes a lot of sense. Plus, with 12" woofers in your old Klipsch speakers, you already have all of the bass response you need for music.
BUT, if you think you might also get into SACD or DVD-A listening at some point, with multi-channel content/mixes, (or things like DVD concert videos), then you might want to get an A/V receiver, and add additional speakers later. Even then you probably don't need a sub-woofer except for movies.
The A/V receiver will also let you play around with various modes of creating multi-channel sound from a 2-ch. source (e.g. PLII, PLIIx, as well as some of the proprietary soundfields that the various receiver vendors have). But in the end there is a good chance that you go back to straight 2-ch. listening for all of your 2-ch. music source material. For that reason you might appreciate a receiver that offers some form of "Pure Direct" mode that bypasses all or most of the signal-processing circuitry, for when you are listening to 2-ch. music.
When I listen to music on my system I am usually in 2-ch. "Pure Direct" mode (my receiver is a Yamaha, but I think Denon uses the same name). So to some extent I wasted money on the other 5 amplifier channels and all of the signal processing circuitry, that I could have put into a higher-quality 2-ch. amp. But, I also watch movies on my system. Not to mention concert videos in Hi-Def, with Dolby Digital mixes. So even if your focus is on music, there may still be reasons for a muti-channel receiver.
