Jeff Rowland Concerto or Simaudio i7 integrated?

With the Super Towers?
With which source?
What do you exactly mean by "more refined"

Thank you both.
Very interesting. Adding your commentaries and suggestions, I think the Sim would be better match for my speakers (very fast and revealing). They maybe only lack in the the very low bass (below 30-35 Hz) part of the spectrum.

Thanks again for your inputs.
I finally settled on something totally different. From T+A (Theory + Applications); a German firm.
Integrated: http://www.taelektroakustik.de/eng/ta2/r_system/pa_1230_r.htm
CD: http://www.taelektroakustik.de/eng/ta2/r_system/sacd_1245_r.htm
I got the CD player as a demo and bought the amp new.
Very fast, wide-bandwidth components. Neutral and very detailed (but not harsh) sound. Extremely well designed; compact yet very powerful. With my Tylers, they make for an incredible system.

If you click on the link (integrated), it will bring you to the page describing the 1230. I bought the PA1230 (100 watts/channel). More than enough. I was very tempted by the 1530 (150 watts/channel), but it was beyond my budget.