Help! Receiver or preamp? Im overwhelmed...

The Oppo suggestion would be good if they hadn't been out of production for at least two years, with used units going for 2x (or more) of the original purchase price.  The new Anthem multi-channel units look good, although if you're keeping your 5-channel amp not sure why you want a unit with internal amplifiers.

@Fatdaddy I guess because AV processors seem to be over the budget and receivers that have internal amps seem to have a lot going on for a reasonable price. You would think units without amplification would be less than those with...go figure.

You can get a used Marantz AV7702 MkII unit for $1000-1300.  I would recommend them because they have excellent power supplies and are the only processor at this price level that have fully discrete analog output stages.  That being said, they do have soft and rolled off high frequencies.  Excellent impact, but if you are using a warm sounding amp it may become too warm/slow.  The Emotiva XPA-5 is a very fast/bright amp and would not have this problem.

The Anthem is going to have much faster attack and better high frequency response, but it could come across a bit bright, especially with your XPA-5 amp.  I don't know that I would go with a AVR receiver because they typically used a single shared power supply for both preamp and amp sections and they aren't that big of a deal.  The processors generally have much better power supplies and are dedicated to preamp only.

If you want something new, the Outlaw 976 is really the only option within your price range.  It's voiced similar to the Marantz 7702, but it doesn't have as good of a power supply and the user interface is rather cumbersome.  It also doesn't have the discrete analog output stages.  The Marantz is a better product here, but you have to buy it used.  The AV7702 is not going to be more than 3 years old (not really old at all).  The 7702 is also pretty current for HDMI (4K and HDMI 2.0 support).  There's actually a mkII on audiogon now for $1,000 even.

Denon doesn't have a processor, so you'd have to get an AVR receiver.

@ auxinput, Wow. Thank you for that detailed explanation. And darn it, right when I was thinking of sucking it up and getting the new Anthem MRX 540 at $1600...

I'm a big fan of Yamaha AVRs. I've posted this before that Pioneer home electronics was bought by Onkyo and then Amazon and Best Buy discontinued sales of Onkyo products in 2020. Marantz and Denon were bought by Sound United in 2017. Usually, but not always, when this happens companies are looking to use the names of the companies only and they often look for ways to keep prices the same but use lesser components. Again, this doesn't always happen but it frequently does. I'm not saying it happened in either of these cases, but you can proceed at your own risk. Yamaha on the other hand, continues to make their own AVR equipment and typically has the best reliability ratings of any audio equipment manufacturer.