The back of the S4 is pretty much what you'd expect: a couple of spare sets of RCA stereo inputs, a mic input, TRS and RCA outputs, a MIDI passthrough, and a footswitch jack if you're into that sort of thing.
As Ian Ayres (my colleague in forbes columny) writes in his insightful and delightful Super Crunchers (Bantam 2007), the technologies for assembling and mining huge data sets have converged over the last couple of decades, and they give us remarkable new power to pluck the future out of the past.
To better understand the potential success rate for a couple entering retirement, stock market history can be dissected into five ranked sets called quintiles.