NAD, Rotel, Maranzt, and Harman-Kardonn are all excellent brands indeed. The “sound” is very much different, though, and depends on taste (well, duh ;)). I, for one, think H-K amps sound much too “warm”, too “cosy”. I like the clean (if at times a bit harsh) sound the Rotels deliver. The NAD and Marantz amps would be somewhere in between, in that respect. Another suggestion is the British brand Arcam. Relatively unknown, but they make amps that (too my taste too “warm” again) IMHO are comparable if not better than H-K, and for significantly less money at that. Onkyo and Denon are NOT high quality components in my book. They’re better than Technics and Sony, but that’s about it.
Stay away from Bang and Olufsen at all times. It’s crap.
CD players: you want one that’s as neutral as possible. Don’t bother about specs, don’t let the salesman talk you into buying high-tech shit you don’t want. Hook up a decent amp and speakers in the store (both preferably neutral sounding ones), and compare CD players. Choose the one that sounds the most neutral and detailed. In my case, that certainly meant a Rotel. They use Philips components (which of course Marantz does as well, seeing as it is Philips’ luxury brand), but they re-engineer the player so that the wiring is better, and more importantly, shorter. Plus, the line jacks are of higher quality than the comparable Philips models.
Speakers: as said, this IS the most subjective part. I chose my Tannoys because they have a very detailed, aggressive sound. My stereo is almost incapable of playing background music. It’s cristal clear, and very natural sounding.
There’s very little to recommend in this area, you just have to listen and compare, once you’ve chosen the amp and CD-player. There are, however, a few brands you want to steer clear of. The following brands are just utter crap: Bose, Jamo, Dali. All in different price classes, but all WAY too expensive for what they offer. The first two live on brand recognition alone, and the latter just looks good. (Women love Dalis.)
Brands to consider are Tannoy, Warfdale, KEF, B&W, BNS, JBL, and probably a lot more I can’t think about right now.
Wiring: buy better wiring than the stuff that comes with it, but don’t go overboard. If you’re paying $30 per meter of wiring for hooking up a $400 amp with a $300 pair of speakers, something is amiss.
All info is, of course, IMHO