Hello,
I use a Koetsu Rosewood Signature Platinum. Syntax is correct IMO , SUTs are very expensive, the good ones. Those folks that use the middle of the road SUTs might not have highly resolving systems to notice the artifacts they impose.
Manufacturers use SUTs to avoid a lot of very difficult design decisions and complexity where active circuits could be used. Admittedly, active circuits that are capable of handling LOMCs are very complex and subject to a host of sonic and environmental woes if not executed properly.
In my experience,I never met a SUT that could outperform a properly executed active device. The problem is: you have to pay dearly for the active device. You or I could more than likely build a SUT from scratch or component parts that would work... building an active device would take quite a bit more formal and practical education that the average audiophile would have.
I've tried my hand at DIY and I've built SUTs and active devices that work. I have also experienced home brew active devices that might rival some commercial endeavours. In the end it is about how much money, time and effort your are willing to invest and what compromises you are willing to endure. Time can teach a lot as you experience both sides of the equation so that you have enough practical knowledge to sit on one side of the fence or the other.
I use a Aesthetix Io Signature with two supplies and a Klyne 7. I could live with either, the Klyne is cute.
Good Luck!