The phono stages in every receiver on the market are from fair to poor in sound quality.

I would advise you to buy a Musical Fidelity V-LPS stand-alone phono stage; it will sound much better and you can use it with any receiver or cartridge you want, both now and in the future. It is very compact and can be located alongside the turntable or receiver etc. Its sound quality is so good that it competes with others that cost 3 or 4 times its price.

I would advise you to ignore the power ratings of 98% of the HT receivers; they generally have very little relation to reality and are totally deceptive. The sound quality is marginal and the power supplies inadequate to drive 5 channels well on almost every one.

One that has much better sound quality and a good power supply and amplifiers is the Cambrdge Audio 551R; its power ratings are conservative (not ridiculously inflated like most), and its sound quality is far superior to the rest..

Marantz and Denon are made on the same production line and are essentially identical in performance. They are not the worst, but far from the best. The same company makes both. NAD is better than either, but not as good as Cambridge.

How would the Cambridge compare with a stereo amplifier from Nad or Marantz in a similar price range? I know the marantz make it easy to integrate one set of speakers into both an av receiver and stereo amp.

I'm not quite sure what you mean about integrating one set of speakers into a receiver and a stereo amplifier.

If you buy a receiver and just want two-channel operation at first, you just connect 2 speakers and use it as a stereo amplifier until you want to add the other 3 speakers.

Also, if you have it set up for 5 channels and just want to listen to 2-channel music, that is no problem; nothing will come out of the other 3 speakers.

A system with HT bypass allows playing music through a two channel stereo with its own sources and alternatively the AV receiver to control output to that two channel stereo as its fronts or mains in a multi-channel home theater.

The Marantz PM8004 for example has a power amp direct button which allows you to switch easily between a receiver and stereo amp easily. However, it's still a $1200 amp. Is there anything in the 1000-2000 dollar range that would match something like the Marantz in terms of stereo sound quality?

If you just want to do stereo for now, there is an amplifier for $499 that sounds better than ANY Marantz amplifier; the Music Hall A15.2. Music Direct sells it.

Maybe you should consider that. It has a phono stage that is not too bad, also.

Get a good stereo amplifier and speakers now, and maybe that's all you will want. I have a 2.1 system and am quite satisfied.

A set of PSB Image T6 speakers with that amplifier would sound very very good.