Agree with the skepticism regarding adding an amp to this particular AVR. Maybe if you are running some Magnepans with under 80db sensitivity that live below 4ohms.....and you sit far away and don't use a subwoofer!
But to answer the second question: "worth it"? Sure, it's fun to look at on the rack, and if you have already got multiple subwoofers set up correctly, a good selection of room treatments, excellent revealing accurate speakers, and all the stuff that makes a big difference, AND THEN you have a couple grand you want to spend for bling... then adding an amp to a high quality AVR can be sexy. (Just don't measure it objectively because that will deflate the sex appeal.)
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And I say this as someone that has fallen down the "add an amp" rabbit hole three times. The last time I said "well, this one is made by Mark Levinson, so it HAS to make a difference!"
Nope. Glad I had bought it second hand and was able to sell it without a big loss after running it for a year.