I haven't seen anyone post anything in the forums about that particular PC. My first reaction to it is that while it may be just fine for running Sonar, it looks like some design exercise with compromised limitations that I would myself take a pass on.
It has an i5 CPU, but it is only running normally at 1.3 Ghz. A look at other available i5 CPU's (not available for this model - just referenced for speed comparison), shows that other i5 processors run at 3.0 - 3.7 Ghz, and have quad cores, rather than two cores - on the CPU that is in the PC you are asking about.
The 4250 i5 CPU in this PC rates 2136 on a performance benchmark scale, while a middle of the i5 road 4590 CPU comes in at 3247 on the same benchmark tests. Point being here is that this CPU is weak on performance.
In addition, while this supports up to 16 GB of memory, there a giant bunches of mATX motherboards out there that support 32 GB and some that go up to 64 GB. For right now, 16 GB is plenty of memory for Sonar, but if you will be using this machine for 3-5 years, wouldn't you want the option to put in more memory than 16 GB? 5 years is a long time to be locked in on something that is mediocre at best from the onset.
Also, the memory is running at a different voltage than what is pretty standard (1.5 volts) - this memory runs at 1.35 volts. I just did a price look up for memory running at 1.35 v as well as 1.5 and for 16 GB of memory you will pay about $50 more for the 1.35 v memory than what you would pay for the 1.5 v memory. ($199 for 16 GB of 1.35 v versus $149 for 16 GB of 1.5 v)
I myself would take a pass on this kind of PC. It's design is goofy and compromised in too many ways for running something like Sonar except for its smaller size (which in my opinion works against it).
The graphics capabilities as implemented are weak, for instance you are limited in resolution choices if you want to use 2 display monitors, AND this model PC reportedly runs quite hot when running multiple monitor configurations (2 displays).
For too many reasons, in my opinion, this PC comes up way short for being a good choice.
I hope that gives you some reasonable guidance,
Bob Bone