Realistically, what your post is going to accomplish is bring out the Audyssey fan club and the Pioneer MCACC defenders/supporters, each will give you the usual reasons for their being on one side or the other
Audyssey 32XT- best variant, most filters, EQ's subs, unless you cough up $750 for the Pro kit, you have no ability to change how it EQ's your setup, other than a completely manual graphic EQ option which negates the advantages of using it in the 1st place.
MCACC - can manually tweak every settings, some still prefer its "sound" over Audsyssey, has interesting and useful features like Phase Control (which does work BTW and has its fans, like me, based on how it worked to integrate an unusual center speaker combo I now have), and even tho it doesn't EQ subs per se, it does have 3 parametric standing wave filters which work as notch filters
I can post my impressions of how well the Audyssey-based SVS AS-EQ1 sub EQ worked for me compared to a Velodyne parametric EQ'r but it will take up more space than you may want to read
Let's just say the improvement, for me, was subtle at best
As far as other features, you will have to evaluate how important each one is to you. For example, the Pioneer has an async USB DAC port for optimized jitterless transfer of audio files, while the Denon has a built-in ethernet hub. If it were strictly on value alone, let alone the debate of whether you can audibly hear the difference, the USB- DAC feature is unique to Pioneer, no other receiver has it, it's only found in external DAC's which can cost hundreds to thousands, while a 4 port ethernet hub (and not even a switch
) is a $10 item, a dime a dozen off off any online PC site
Both are excellent choices, you can't go wrong with either. I've been using Pioneer's class D amps since the original SC-09 flagship. They are clean, hi-powered, handle 4 ohms easily. But then again, Denon has also now officially sanctioned the 4520 for 4 ohm use, so...take your pick
The sound quality of the SC-68 is excellent but I'm sure the Denon 4520 is too.
Can you find both where you're at (Baghdad
) and compare in the same room with same speakers? That would give you the best opportunity to compare how Audyssey & Pioneer's MCACC can sound in a setup. But I realize your opportunities may be limited there. Have you downloaded the manuals yet?
hope this helps
Obviously we don't know if you live in Iraq or one of the forces, but either way, hope things are going OK for you