I have no experience with the Stereovox, but hopefully some of my findings below will help you:
I compared a Kharma Enigma 75 ohm Coax Digital ($3500) to a Kubala-Sosna Emotion 110 ohm AES/EBU ($1600) so some of my findings may be due to the differences in design.
The Kharma had a more forward midrange when compared to the Kubala, and the bass was not as robust as the Kubala. The Kharma's bass was a little leaner, when compared to the Kubala, however the bass was always tight. The treble on the kharma was a little zippier than the Kubala. The Kharma's low level resolution was slightly better than the Kubala, which surprised me since I felt the Kharma Cable was not as quiet as the Kubala. This finding probably had more to due with the slightly more forward midrange of the Kharma.
The Kubala was better balanced from top to bottom. The bass, midrange, or treble never stood out. The bass was full and tight, The midrange was luscious, and the treble was silky smooth. The Kubala also had a more laid back soundstage, behind the speakers. I also felt that the soundstage was slightly deeper and wider on the Kubala. I preferred the fuller bass of the Kubala, yet it was never bloated. The sound of the Kubala was also very musical and coherent. The Kubala had a quieter and blacker background, but some of this was probably due to the AES/EBU input.
I did find the Zu Ash very revealing, and very much to my liking, with tight bass, and well balanced from top to bottom, with no frequency range sticking out greater than the rest, it also had a slightly less quiet background than the Kubala that may explain the slight touch of grain or hash that I heard in the midrange that I was told would go away with continued listening, it also had a slightly smaller soundstage than the Kubala, but it was still very deep and wide. The imaging and focus was also very good. However, after I put the Kubala in my system I returned the Zu Ash, based on their 30 day return policy at the time.
Keep in mind that the Zu Ash is a $300 cable and the Kubala Emotion is a $1600 cable.
Incidentally, there is a Kharma Enigma Digital cable for sale here for around $1750, if my description sounds like a match for your system.
I don't know what your budget is, but I'm thinking that the Kubala may be too ripe in an all tube system, and the Zu Ash or the Kharma, would probably be a better choice.
I'll give you an analogy (hopefully you have some experience with the products that I'm describing). The Zu Ash is similar to the Benchmark DAC1; as the Kubala Emotion is similar to the Bel Canto DAC3.
I think that the Zu Ash would be a great match for an all tube system. I would have been happy keeping the Zu if the Kubala hadn't come along.
"I think you should go get yourself a nice piece of Ash."