Joe,
I understand what you mean by bass deficiency compared to the Summits... and I see what you mean by "having the Vantage run with a sub" should make up for what it lacks relative to the Summits. I have an SVS PC+ subwoofer at the moment, but I dont think I can keep it if I want to afford the Vantage - I will have to sell it.
So, I will be left with the Vantage and my Rotels... everything else (including the $1000 headphone setup with amp) will be sold.
But.. what a nice computer speaker system it will be!
I think after I purchase the Vantage, I will start building around it more... like a better DAC, a better source, and perhaps a better amp... someday.