Just to clarify, when I mentioned the $1700 delivered price, I was talking about the cylinder SVS Ultra, not the box, which is $2000 delivered, like you said. The P
C13-Ultra DSP, not the P
B13-Ultra DSP
As far as performance between the SVS Ultra and the eD A7-450, I can't claim to have heard a direct head-to-head. I have heard the newest SVSound PB13-Ultra DSP, and I have heard the eD A7-350, which, obviously, is a smaller 15" sub as compared to the A7-450, but it uses the same amp and a similar design in other respects (eg. design and general component structure of the driver, build quality of the cabinet, etc.)
To put it plainly, the PB13-Ultra DSP is the best subwoofer I have ever heard, save for the extremely expensive JL Audio Gotham g213. There is far more to a subwoofer than just sheer output. And, indeed, it might be the case that the A7-450 can produce higher SPL, given its larger driver. But the question is: at what sort of distortion level and with what sort of accuracy and linearity?
No question, the A7-350 that I heard was capable of tons of output. But it did not possess the same tightness and control as the newest SVSound Ultra and Plus subwoofers. It's rather hard to pick out distortion in really low bass by ear, but, without question, picking out distinct notes in deep bass passages was far harder on the eD than on the SVS, which typically indicates higher distortion.
It's also important to not be fooled by specs given on digital amps. The Sledge amp in the SVSound subwoofers these days is the most sophisticated and capable amp I've come across - and that's without any consideration of price. While the amps used in eD's subs might be able to hit the claimed 1300 Watts for a second or two, they can't sustain that sort of power output in real life. The SVS Sledge amps, on the other hand, can actually deliver their spec'd output, and do so over a lengthy period of time.
If you're worried about output capabilities of the PC13-Ultra DSP cylinder, I have my own listening experience, which was a heavily damped 23' x 27' x 9.5' dubbing stage, in which the PB13-Ultra DSP was able to play louder than I could personally stand for more than a few seconds. And to back that up, there are the recent Audioholics measurements, which indicate that the PB13-Ultra DSP can hit 115dB output levels with a 2 meter measuring distance in a quasi-anechoic environment, and can CLEANLY deliver 110dB SUSTAINED output all the way down to 20Hz with rather ridiculously low distortion.
Could the A7-450 play even louder? Like I said, I can't say for sure, since I've not heard it for myself. But given what I heard with the A7-350, I rather strongly doubt that the A7-450 can deliver the same sort of sustained output levels, and I'm virtually positive that it cannot match the linearity, transient response and low distortion.
The PC cylinder version brings the delivered price to well within the same ballpark. And it's worth noting that it's a mere 16" around, meaning that it takes up rather little floor space. If you're ok with a tall tube, rather than a huge fat box, there's no better value that the PC13-Ultra DSP for your usage, IMO.