I bought an Onkyo TX-SR505 receiver and really like it. It has a lot of good features, will drive 4 ohm speakers (despite what the manual says), and accepts a variety of signal inputs. However, there is one missing feature that I would really like to have: pre-amplifier outputs. This would allow the use of an external amplifier and additional signal-chain devices (such as a graphic equalizer). I feel strongly that room compensation with a graphic EQ is important, but that is a topic for another post.
I opened the cover on the TX SR505, and eventually found a convenient place to tap into the pre-amp signals. I used some short lengths of shielded cable to connect three newly-added RCA jacks to three points on the main audio board. Note that the cable shield is only connected to the metal receiver case at one end. I think the photos will explain everything better than I could in words, so take a look.