I wanted to follow up with some thoughts about the receiver as well.
Yet again, seperating the bass would
definitely be the way to go if your dad wants to use a receiver rather than seperates with a more powerful seperate amplifier. Trying to drive a full range signal with a receiver would NOT be a good idea and would not produce good results at all in a large room. Again, bass requires moving a lot of air. That means either moving woofers with a large physical area, or moving woofers a great distance in and out (the excursion) or both! Either method requires a LOT of power and a receiver just won't deliver it.
But have a subwoofer produce the bass instead, and once again, the story changes! Now the subwoofer uses its own internal amp to drive its own large woofer. Now the receiver only needs to power the smaller drivers of the slim speakers and only has to worry about frequencies from 80Hz on up. This is a much lighter load. And a receiver will be much better able to handle this task!
If you're looking for any receiver recommendations, I really would have to give the nod to Denon right now. For one, their power section (amps) are solid. I'm sure you've read reviews - Denon has a very good reputation for solid, well performing amplifiers in their receivers.
But more than that, with their 09 series lineup, they've really added some excellent new features IMO - almost all of them having to do with Audyssey.
In a large, open room like this, you're going to have some odd room interactions with the sound - it's inevitable really. While the tip top solution involves paying a professional to come in and do a real time analysis, the next best solution is to use a very good auto-setup/calibration. And in that field, right now, Audyssey is the tops - without question IMO. Yamaha has their YPAO, Pioneer has their MCACC, Harman Kardon has their EzSet/EQ - none of them are as good as Audyssey IMO. I'm just one guy who's tried them all, but that is my opinion. Not saying the others are bad, just saying I think Audyssey is the best. But there's more as well!
Audyssey has also introduced some new technologies: Dynamic EQ and Dynamic Volume. Strictly speaking, you may not want to use these features since they do alter the original signal, but in my experience with them, they most certainly can enhance enjoyment in a lot of situations.
So the Audyssey technologies start with MultEQ, which as I said, I think is the best auto-setup/EQ for home receivers right now. Some models also add BassXT, which ends up making the name MultEQ XT, and in this situation, that could be a great feature to have as well. BassXT extends Audyssey equalization down to the subwoofer and also adds a certain level of protection. During setup, BassXT examines the subwoofer's response and essentially learns its limits. This allows the receiver to send an EQ'd subwoofer signal that can produce flatter frequency response. It will also stop short of sending signals that the subwoofer cannot reproduce without bottoming out, so that is where the protection comes in.
Dynamic EQ is a fantastic feature IMO. Basically, our hearing is the most "flat" at 85dB. In other words, regardless of what frequency is played, if it is played at 85dB, we more or less perceive it to be equally as loud as any other frequency played at 85dB. And that is why 85dB is "reference level".
But below 85dB, our perception of sound is not at all "flat". The quieter the volume level, the worse our ability to hear bass and very high frequencies. Basically, we are evolved to best hear mid-range - which makes perfect sense, since that is the realm of the human voice.
What Dynamic EQ does is intelligently adjust the frequency response. Most people find a median 85dB listening level to be too loud. It may be "reference level", but our typical "enjoyment level" is closer to 75dB. This normally creates a problem, now the mid-range is pleasing in volume, but we're actually losing bass and treble. The signal is all there, but our ears are blanking some of it out. Dynamic EQ adjusts the response so that it once again
sounds flat to our ears. So now you can listen at a more pleasing volume level (ie. quieter) but still hear the
balance between all frequencies from low to high the way it was intended.
Dynamic Volume is a great feature, but only sometimes IMO. For serious listening, turn it off. But for TV watching, I think it's awesome! Dynamic Volume addresses the common problem where TV ads sound WAY louder than the program and where some channels are way louder than others. I think we've all come across this annoyance and Dynamic Volume largely solves it. This is not just straight up dynamic compression. This is not Dolby Night Mode where a huge amount of detail is lost. Dynamic Volume DOES compress the dynamic range - which is why for serious listening, you want to turn it off - but it does so far more intelligently than older technology and it uses MutlEQ and Dynamic EQ to retain detail while it's at work. For TV watching, I really think it works great. It's not flawless, but it goes a long way in reducing the panicked scramble for the remote to turn down the volume when a commercial comes on!
So it's awesome to see this full suit of Audyssey technologies in Denon's receivers and that is why I recommend them
