Some very good info and recommendations for you here. I wouldn't change a whole lot. Only thing I could do is offer a few other options.
I happen to like Onkyo in the lower price range for receivers. I just happen to like Audyssey the best out of the auto-setup options and Onkyo delivers a ton of features and solid power output with their lower cost receivers. The TX-NR609 would be the most likely candidate for your price range.
One thing I'll mention on the receiver front though - if you've some way to afford the Onkyo TX-NR709 at about $550, that's a really nice upgrade. The reason is two-fold:
1) It's about the least expensive receiver that offers pre-outs. The reason pre-outs are important is because it allows you to add a separate amplifier in the future if you want to. Without pre-outs, you're stuck with the internal amps of the receiver no matter what. You might never use an external amp, so this is purely optional. But I personally think it's nice to be able to use external amps if you want to, and the TX-NR709 is a very affordable way to get yourself this option
2) It's the least expensive receiver that offers the higher level Audyssey MultEQ XT. There are a few "levels" of Audyssey, with each higher level offering finer adjustment of the EQ. The biggest difference though is in the control over the bass from the subwoofer, which is where EQ has the most benefit and makes the biggest difference. MultEQ XT has considerably more control over the bass, so to me, that's a worthwhile upgrade.
For the subwoofer, I have to reinforce that it makes total sense to spend proportionally more on the subwoofer than other components in your system. Reproducing deep, accurate, tight, clean bass is not easy! And when 50% of your listening is music and 50% is movies, you really do need a sub that can "do it all" and play both deep AND clean.
For that, I'm in full agreement that you basically have to get up to at least about $500. You have a medium sized room with openings though, so getting loud output is going to be a challenge for any sub at that price. It's just a matter of having your expectations in the right place. Most people don't listen at anything close to reference volume. Reference volume is 85dB average with 105 dB peaks in the speakers and 115dB peaks in the subwoofer! This is tremendously loud, so most people aren't anywhere close to that in their normal listening at home. So long as you're not expecting reference level output, a $500 sub should do just fine for you.
I personally think the Rythmik FV12 is the best $500 sub at the moment. It plays deep, hitting just below 25Hz and just above 20Hz. Best of all, it's very clean, accurate and "tight" compared to the competition at this sort of price level. What I perhaps like best about it is that it is extremely well engineered so that you cannot damage it or cause it to produce tons of distortion. It will simply play as loud as it is safely able. You can keep turning up the volume, but the FV12 simply won't play any louder than is safe. So you might run out of volume and headroom, but at least you won't damage the sub or get some really nasty distortion out of it
Given the openings to your medium sized room though, you might want to go for as much output as your budget will allow. Keeping the nice accuracy and articulation intact, I would recommend the Outlaw Audio LFM-1 Plus at $549. The LFM-1 Plus is basically a clone of the old HSU VTF-3 MK2 (it just has a different port location, everything else is the same). The LFM-1 Plus can generate some very healthy output and still retain good extension down to 25Hz and nice, accurate sound with good transient response. It's a very nice sub and capable of a bit more output than the FV12, so it's a very good option for a situation like yours.
For the speakers, I tend to favor "large bookshelf" speakers. Towers are often about getting deeper bass extension. Having more drivers and a larger cabinet allows towers to play louder than small bookshelf speakers. But often, towers are designed to simply try and play as low as possible, which isn't something that you need when you have a subwoofer!
I personally prefer to use a speaker that is tuned and designed to only play flat down to 80Hz where the subwoofer will take over, but still uses more than a single woofer in order to increase output and efficiency. So that leads to my fondness of "large bookshelf" speakers that often cost less than towers, can play just as loud, but just can't play as low, which you don't need anyway when you've got a sub!
Personally, I'm a pretty big fan of
Ascend Acoustics' CMT-340 SE speakers for a setup and budget like this. The SEAS tweeter in the Ascend speakers is really something special - a WAY better tweeter than you'd normally find in this price range. The CMT-340 SE also have stands that basically make the speakers look like towers.
So, like I'm so often prone to do, I've just increased your total price tag
But it's all about nice, worthwhile upgrades that I think are completely worth paying just a little bit extra for. Many people say that they want to know about the products that might cost just a little bit more, but are really worth the extra few dollars. I don't think anybody likes it when they spend less, but discover later that something significantly better was available if they'd only known about it
Anywho, like I said, all I've got are some more options for you. To be clear, I can TOTALLY get behind the recommendations that you've already received! To me, the subwoofer is the key here. If you spend a little extra anywhere, spend it on the sub. It really is the thing that takes you from "sound" to "theater sound", and it's what really adds the excitement and gets the "wow" reaction that most of us are looking for
Merry Christmas!
