Picking the best receiver out of what I have

(wasn't sure on where to put this so I cross posted it to 2 channel audio)

So I'm a little bit of an audio noob, but I've managed to collect a few different components over the years. My problem is I'm not sure which I should be using to get the best 2 channel audio sound quality (this is what the system is used for 90% of the time).

I will be playing mostly vinyl, some CDs, and a lot of (high bitrate) MP3s off of my HTPC on this setup.

I have the following receivers:
Toshiba SA7150
Onkyo HT R500
Pioneer SX-424
Kenwood KC-207 (with Kenwood KM-207 amplifier)
Yamaha HTR 5890

The Toshiba would need to be repaired for me to use it, though I'm suspicious it would produce the highest quality sound of those listed. I have the repair manual and some knowledge of electronics--if it would drastically improve SQ I would be willing to take it apart and fix it.
The Kenwood stuff is part of that huge Spectrum 87B system they sold back in the late 80s. If it helps, I'm also using the speakers from this system (JL 975 AVs I think).

I have two turntables, one that came with the spectrum system, the Kenwood KD-87F, and an older Kenwood KD-2033. I have no idea if SQ varies between turntables or if either one of these is superior to the other.

So my question is: among this equipment, what would you guys use for the best 2 channel music quality? Does having a seperate amp (kenwood receiver/amp) make a noticeable difference, or would I be better off using the newer, nicer Yamaha? Is the Yamaha's built in amp better than the Kenwood KM-207?

And will the same setup produce be best for both a vinyl source and an analog (or digital?) signal coming from a PC? Or would one receiver be better for the vinyl while another (the Onkyo and Yamaha both have optical) would be better for MP3s?

Thanks for reading and thanks in advance for any suggestions or comments

Andrew
andrewc2232 is online now Report Post Edit/Delete Message

correction, the toshiba is actually the sa7100. It is rated at 110watts at 8ohm, 140 at 4ohm.

would there be any downside to running the turntable to the kenwood and then passing it through to the yamaha?

sounds like I just need to take this stuff out and spend some time playing around with different configurations

I used the pioneer for a little while temporarily while I was still moving into my new place. It is definitely a sleeper, but the Yamaha seems to put out a much better sound. Also, it does have phono inputs.