Did some research...
For the money, the Scan-Speak driver I mentioned above is, in my opinion, the best option out there. If you want to spend less, I recommend the Dayton Audio HF subwoofer drivers. It is clean, powerful, and plenty loud - though it needs larger enclosures if you want the best performance.
The amp you linked to has a boost at 30Hz, which is not necessary in a vented subwoofer and thus not appropriate for this project (I assume a larger vented sub is preferred). The same amp without any EQ boost in the bass would be better (
LINK).
Now, to the logic - I like to look beyond just a spec or two on the driver and instead look at the entire system.
A woofer with a higher Qts tends to be looser and floppier, so a tighter enclosure, such as sealed or if vented being less resonant, can help with that and solve any potential issues with sloppy bass rumbling too much when it shouldn't. A woofer with a lower Qts may not suffer as much from "ringing", but it also won't have the same bass extension, so to make up for that a vented only design with a huge resonance to help boost the lower part of the output can assist with the performance, but lead to other issues. I find for vented enclosures a Qts between 0.32 and 0.40 is best - but other parameters come into play such as linear excursion, Vas, Fs, and power handling.
A higher Vas is typically associated with higher sensitivity, but it also forced you into larger enclosures if you want deep bass. But a woofer with a low Vas typically has limitations on peak SPL output and such. So, I tend to ignore it until I have to choose between an ideal refrigerator sized enclosure or something smaller.
Power handling is important because bass is not well heard by our ears, as explained by the famous equal loudness curve. So if you want audible bass below 40Hz, it has to be louder than you need at 100Hz and even then if you want it to have dynamics of any kind it has to be even louder. So, a speaker which can handle enough power AND generate enough output below 40Hz, like 110dB SPL, with an amp you can afford would be preferential. Otherwise you need more woofers, enclosures, and amps to make up for lack of max output. Power handling and sensitivity go hand in hand. If the sensitivity is 90dB SPL 1W/1M, then a 100 watt amp will allow the speaker to play as loud as 110dB SPL at 1M in an anechoic environment. If the a different woofer has a sensitivity of 96dB SPL 1W/1M, the same amp can drive the system to 116dB SPL at 1W/1M. That would be perceived as twice as loud. BUT... you also have to take into account peak-to-peak excursion when considering peak acoustic output. Just because the voice coil may not burst into flames with 100W of power driving it, the cone may reach its limits at 75W and anything louder will be distorted and suffer serious dynamic compression giving you that loud steady rumbling in the room while all the sound seem like they should be punchy and dynamic. This is one of the common limitations of affordable off the shelf subwoofers. So, I shoot for a system which can be modelled to perform well at levels about 6dB to 10dB louder than I would ever imagine needing, that way any mistakes in my calculations, manufacturer specifications, or cabinet construction won't limit my real performance.
When I model a subwoofer I assume the bass output is pretty useless at the -6dB SPL point on the response curve. That is just me playing it safe, as room gain can increase the output by as much as 20dB SPL over the measured and modelled anechoic performance. That's a ton of output gain and one reason many home built and even commercial vented subwoofers sound overly boomy and seem to lack "tightness". However, room gain is very difficult to predict until the sub in installed and tuned. So, it is hard to design around unless you really know the room from past experience. The multi-port with foam inserts approach from SVS is one very acceptable way to retune the sub enclosure to better match the performance to the room. My own family room is big boomy, thumpy, echo filled room to start with, so when I sought out a sub and considered building a sub, I knew a sealed sub would be best. This is especially true since I have no plans to address the bass acoustics at all, what with this being a gathering place with a decent stereo - not my reference system. Better would be an infinite baffle, but that's a completely different story. Still, we have to deal with whatever we've got, right?
I like the Scan-Speak driver as it has several specs I find preferable in a subwoofer - low Fs, reasonable Vas (as related to the low Qts), and high enough power handling and sensitivity to produce prodigious bass below 40Hz in a proper enclosure.
If you could tell me about your friend's room where this sub will be installed, I could recommend some cabinet tunings to get a decent performance in that room.
