Thanks for all the replies. I have to admit, I like the flexibility of the Scarlett 2i2 for some possible future project ideas. I also have a Topping d30 and d10 kicking around, so that would clean up the 8kHz spikes on the DAC side of things. Though I must admit, the QA401 scratches my test equipment itch. That said it's running at $450 whereas the Scarlett is $150 from amazon. I'm thinking it's best to go the middle road until I hit the limits of my test gear, and I'm pretty sure my amps won't be near that.
I have an older Bitscope 120 (http://www.bitscope.com/product/BS120/). I think I've only used like 10% of it's capabilities. I don't need it very often, but when I do, nothing will substitute. I just realized I'm having an intermittent problem with a internet remote I built for my AC and I should wire it up and try and capture it failing in action.
Hi Chris, dont know if you are interested but I might be changing tack with my measurement kit, so I may be selling my QA401 in the very near future and / or my Motu 8A. I will know for sure after the weekend.