As others have noted, I’d expect a component tuner to be superior to what would be included in a receiver. Keep in mind that probably no more than 25% of the cost of the R-S300 is going to be tuner, and probably even less than that (I have no factually data on that, just my seat-of-the-pants guess). The rest of the money goes into the pre amp section, amplifiers, all the connections, etc. – none of which you have any use for.
Personally, I’d pass on the T-S500 and see if you can score a vintage Yamaha TX-950 tuner. I used to have one and it’s a fabulous piece, probably the best Yamaha ever made. It was lauded for its excellent sound quality and ability to pull in distant stations. They listed for $400 in 1990 – what is that, about $1000 today? – but sell under $100 on ebay these days.
Regards,
Wayne A. Pflughaupt