That unit gets rave reviews. While I don't imagine it gets many people combining it with tube gear, it's one of the best EQ's in its class.You'll find two different schools of thought here. Some would prefer a simpler solution for home use. Others like DSP and computer control. You're suggesting a blend of the two by connecting something like this into an otherwise all tube system.
No harm in that - It's probably not appropriate to say it's "good" or "bad". Certainly, this unit is one of the best EQ's, providing a lot of response shaping and signal processing features. You can do a whole lot more with this unit than most home Hi-Fi installations require, and maybe more than some would want.
I'd say it will probably be excellent, but you might want to resist the temptation to over equalize and play with the features. Set it up and leave it alone; Don't use response shapers more than you need. If you use the delay, do it systematically and know exactly how much you need to compensate for physical offset.
There's no harm in having fun with a unit like this, but without proper setup, you can really make a system sound bad. When properly used, it should be subtle, like it isn't even there. In my opinion, if you can "hear" a signal processing device, then it is not being used well.