The thought of having acoustic panels or some geek from a sound company come out and charge me to tell me how far out from the wall and where my speakers need to be placed is a joke. I can see if you have $25k worth of high end home theatre equipment but I'm a simple guy that's just looking for a decent reciever to run his modest system.
But the joke maybe on you. We are trying to make you understand how much the room, placement of speakers, and listening positions have on the sound - WAY!!!! more than any silly amount of money you will spend on equipment. This is a cold hard fact.
More than once I have done an audio system for a customer (an example of $10K comes to mind), that I designed, installed, and calibrated. The customer was thrilled with it and wanted me to look at a friend's system. The friend had spend well over $50K on his system and sounded meh.... (translation: not so good). Why! Because either him or someone else (I didn't ask) had just bought a bunch of equipment and hooked it up with no regard to the listening environment (i.e. they didn't really know what they were doing).
The conclusion to this:
If you just want a surround sound system and not spend a lot of money... great, that's fine. Do take the time to research and learn to try to get it as ideal as possible. The difference in a budget sound system sounding good or sounding like crap is how well you follow industry standard guidelines for this kind of stuff. And there are industry standard guidelines (a lot of them), you just have to really read and research the topic.
If you want to have really great sound and spend a lot of money on equipment, then you NEED to hire a professional as part of the budget to help with the room. Only 1 exception to this: If you are already a good sound DIY that has a lot of expereince working with rooms and sound systems.
If you were happy with the Marantz receiver and don't want the possiblitly of making a mistake in another brand, then get another Marantz (it is a good receiver). If you are happy with the sound you are getting and have no desire to improve upon it, then don't worry about the 'joke' of having it setup properly either. You'll never know and it will be fine - whether it was off just a little or a lot.