The exa is fine, but doesn't function well with the software I use. I think we've talked about that before. It can't do a synchronous in/out. I know you use DIRAC LIVE and it has a method for synchronizing two different clox in/out. But Acourate does not and Audiolense has something to compensate, but I don't really trust it. It's not ideal.
We can go through the list of MCH DACs, I've seen them all and none of them work, other than pro gear. The problem with pro gear is that it's designed for pro environment. So, it's all mixers. I'm okay with looking at a mixer. I think they look cool and I have learned how to use one. But I don't want my wife to get anywhere near one.
Believe it or not, I've blown a few drivers over the years. Yes, it's all my fault and I must be the dumbest audiophile on the planet. Looking at a huge mixer which interfaces with at least two additional pieces of software and multiple ASIO drivers before sending several 15hz-24khz logsweeps, one may find that a lot CAN go wrong. When it does go wrong, it's a huge PITA.
It may be the case that I do as Nyal suggested (offline) and just find some inline resistors to protect myself when I do the sweeps. Then I can use digital volume control for normal listening.