Do I need a subwoofer? Which brand and model?

"11-30-14: Bob_reynolds
Since music is the priority, a sealed cabinet would more likely be a better choice. And there is no reason to get a power amp. You do not want to drive your main speakers more -- this only creates more distortion."

No offence, but that's silly. There's more to audio than reading a spec sheet. And in this case, you're guessing in order to fill in the blanks. In the real world, you're far more likely to get a speaker to distort by under powering it. The OP has a big room and his current amp, while of good quality, is not all that powerful. If a speaker has to be driven harder than normal because the room is big, its far safer to do it with a more powerful amp. You'll get less distortion, not more. (Unless, of course, you're foolish enough to push the system so hard, it starts to break up. After reading the OP's comments, I really don't think that will be a factor here.)

Take into consideration also, that driving the OP's current speakers to their potential, will make it much easier to integrate a sub. The integration works both ways. Just as you can push an amp and speakers into distortion, the same can happen with a subwoofer and the amp that powers it. In fact, you're much more likely to have a distortion problem with the sub, as opposed to the main speakers.

Shugho,

presume you have no ability to try the Hsu at home. you might wish to call Hsu and ask for their advice...specifically the size of your room and basic system components.

As for the amp, i can only suggest you try one at home. Typically i find that the bass becomes more 'solid', defined with greater punch...what i have NOT found is that it goes dramatically deeper or surrounds me in waves of propulsive bass...but for some people, this solidity, definition and punch are what they are looking for. good luck.

"11-30-14: Bob_reynolds
ZD,
In the real world, you're far more likely to get a speaker to distort by under powering it.
You may be confusing the fact that you are more likely to damage a speaker by driving it with an under powered amp since you can drive the amp into clipping more easily. I assure you the driver will distort less at 65dB versus 80dB."

I'm not confusing either. That's why I put this in my last post.

"(Unless, of course, you're foolish enough to push the system so hard, it starts to break up. After reading the OP's comments, I really don't think that will be a factor here.)"

I think its a given that if you turn your system up really loud, it will probably distort at some point. Also, you are doing some guessing.

"Unfortunately, they don't quote an SPL level and distance, but it's likely 85 dB at 1 meter. This tells me that, as is typically the case, too much of the budget went into the cabinet and not the drivers to meet the price point. The distortion could double by 150 Hz and double again by 75 Hz and again by 30 Hz. You will be better off taking the bass load off of these speakers."

That, and the 2 other references are general and not about the OP's equipment. And that's really where your argument fails. Look at this, as well.

"Distortion created by a driver increases with level; just consider the heat. This is common sense, it certainly isn't silly and I'm not guessing. Distortion also increases as frequency decreases. Again, I'm not guessing; it's a fact.
In fact, you're much more likely to have a distortion problem with the sub, as opposed to the main speakers.
Now, that's just silly. You can't seriously believe that a 6.5" driver is going to distort less than a 12" driver when asked to reproduce a 40 Hz signal at 85dB.

That's exactly the problem with driving the majority of speakers full range (they are not designed for it). Speakers using crossovers use high pass filters on their tweeters and on their mid range drivers (if it's a 3-way design). It only makes sense to high pass the woofer when adding a subwoofer (effectively creating a 4-way design)."

In all this, you're missing the most important issues. Quality of the components going into the speakers, the design of the speakers, and the build quality and power rating of the amp. So going back to your example of using a 6.5" driver for a sub over a 12" driver as being silly, may not be the case. If you take a high quality 6.5" driver and put it into a well designed enclosure and power it with a very powerful, high quality amp, there's no reason why it can't outperform a lesser 12" driver with a low quality, low power amp. Not too many people use 6.5" drivers in subs, but there are many examples of 8" designs on the market that easily outperform 12" and 15" subs.

Thank you all for taking the time to help me out. The inputs give me a few things to think about and will help me make a suitable decision. I am inclined to try out a couple of scenarios before I make my decision, based upon the inputs provided. This has been an enjoyable read. I appreciate everyone's help and hope to have a solidly punchy and bassy musical holiday season! Cheers all!