Receiver as pre-amp for outboard amplification?

I don't know your receiver, so take this with a grain of salt.

Receivers don't generally have great pre-amps lurking in them, awaiting a separate amp to be liberated and perform great (I have tried this with a number of receivers). So the limitation of this approach is that you will have (typically) a mediocre preamp when you are done.

This isn't to discourage you from doing what you want, just realize that further upgrades will be possible. If you audition separate preamps in the future, you will be surprised how much difference they make. I found that (within reason) preamp choice made more difference in the character of sound than amp choice.

Check out BV-Audio for an economical way to vastly upgrade you system. I just received their P-1 preamp and am awestruck. I have amps on order from another company (before I discovered BV-Audio) or I would opt for their power amp as well. They also make an integrated amp which, based on my experience with their preamp, is no doubt an excellent product.

+1 on what EHart has said,

I have been down this road as well, I used a Marantz 2245 as a pass through pre when i first got into hifi, I realized very quickly that a dedicated preamp makes a world of difference. There are several options depending on what you want to run. You can pickup an older adcom, emotiva, hafler parasound to even a McIntosh for relitivly cheap, I have seen mx119 and C26s go for 600 bucks which is a steal as they are really good preamps that will last you, just becarful with the choice as some of the mx series does not have a phono stage if you into vinyl. The MX series are home theater preamps but works just as good for 2 channel audio. If you are looking for more, I recommend the Usher 307 but it’s pricy, one thing you can count on is higher end preamps will not color your audio, like a lot of the lowerend gear will. E bay is a great place to look for solid preamps.

i bought a marantz 4300 4 chanell reciever back in the early 70's. i wanted more power so for the money, i bought a phase linear 400 amp to power the front chanells and the 4300 to power the rear channels. in 2000 i purchased a mcintosh mc2205 for 2 chanell stereo. in 2010 i purchased a mcintosh mc 602 amp. i used the marantz as a pre amp but it had too much noise. so now i have a mcintosh mx132 for a pre amp. it sounds better with no noise!