New to Sonar x3 Studio from Tracktion...advice on Audio Interface

I am sure it would work OK but I would not own one. The problem I have with it is similar to it's competition, they are bus powered devices. I prefer an interface which is not bus powered. This usually means a slightly more expensive unit.

I believe most of the 2x2's are bus powered. In the Tascam line the US 4x4 uses a separate AC adapter.

From what I read the optional power supply is used when connected to an iOS device. Does this mean it will also work when connected to a PC?

I would definitely take a look at some of the Focusrite Interfaces.

The TASCAM US-2x2 is designed to take its power from the USB bus with Mac or Windows. However, if the computer doesn't provide sufficient power, then you need to use the optional AC adapter. The US-2x2 must use the AC adapter with iOS devices. The US-4x4 cannot be bus-powered, and requires using its included adapter for computers or iOs.
 
The main attributes of these interfaces are the mic preamp quality, the inclusion of 5-pin DIN connectors for MIDI in and MIDI out, and iOS compatibility (FWIW the Focusrite 2i2 is not spec'ed as working with iOS). Also, the zero-latency monitoring is stereo and crossfadable, not just switched, and TASCAM is now writing its own drivers in-house, which improves performance considerably compared to the previous generation whose drivers were supplied by a third party.
 
Disclaimer: TASCAM is part of Gibson Brands, as is Cakewalk. OTOH that means SONAR gets tested with the interface 
 
Here's an article I wrote about latency that mentions the TASCAM interfaces.
 
Basics: Five Questions About Latency and Computer Recording

AT
Craig, off topic but can you ask the Tascam driver writers if they are working on UH-7000 drivers and whether these can or will be able to be aggregated w/ the newer units. 
 
@

I'm pretty sure you can aggregate them already using WDM, but I don't have the UH-7000 here at the moment to verify.
 
As to drivers, I can ask but there is a fundamental difference in that the UH-7000 includes onboard DSP. The US-2x2/4x4 do not; the materials cost went into the mic pres, adding a MIDI interface, and the enclosure. So I think the UH-7000 drivers would have to be rewritten more or less from scratch. They did do driver and firmware updates last summer (including Yosemite compatibility for the Mac) but these were updates to the original drivers.
 
I tend to think TASCAM saw the UH-7000 more as premium mic pres for capturing stereo audio that could interface with a computer, and as the current drivers work for that type of application, I don't know if there's a lot of demand from the current user base for lower-latency drivers.