Can anyone recommend an FM Receiver that would play into a relatively high end system?

Pick up a cambridge audio t500 used for cheap on ebay, an excellent tuner with a knob for tuning. It is a joy to use and sounds terrific. Alternatively, find a used creek t43, essentially the same as the above t500, but with slightly better performance. I own both, as well as a Marantz st6000, they are all very very good tuners. Connect any of them to an open line input on your integrated. 

Well I would certainly consider a Mcintosh MAC7200 as a high end receiver. I thought there were some other pretty decent integrated amps that had FM card options too.

I listen to internet radio a lot and have thought about getting a tuner for potential extended internet outages and to explore local stations. Using the phone on cell service is a great idea too, but that may become compromised as well in an emergency and watch your data usage.

I'd love to get my hands on a Magnum tuner to play around with. 

Many companies still make AM/FM dedicated tuners. Yamaha for one, see the link below. $250 new. You seem to already have plenty of amp and other devices, just need the tuner. I think that you can find tuners like this without needing to go some over-the-top complicated setup.
https://usa.yamaha.com/products/audio_visual/hifi_components/t-s500/index.html

I remember seeing an ad for a used FM tuner that could also receive satellite radio (Sirius/XM); but, I can't remember which brand(s) it was. But, if your goal is to have as many listening options as possible, that could be a potentially good candidate.

mitchagain

I remember seeing an ad for a used FM tuner that could also receive satellite radio (Sirius/XM); but, I can’t remember which brand(s) it was. But, if your goal is to have as many listening options as possible, that could be a potentially good candidate.

Several tuners have offered this option, including McIntosh, but it’s a poor choice. SiriusXM’s online stream is much higher audio quality than its satellite signal.