PEQ or XLR

I'm currently running a 2.0 channel music setup in my bedroom consisting of a:

Sources: Panasonic BDT-10A BR-DVD-A (Analog) / Logitech Squeezebox Touch (Coax) / Apple TV (Toslink)

DAC: PS Audio Digital Link III

Integrated Amp: PS Audio Trio C-100

Speakers: Sierra-1 NrT

I want to add a sub into the mix and deciding which amp to get on a Rythmik F12 with the option of getting a second sub if I move my setup to a larger listening area. The Trio C-100 has stereo line level outputs but no bass management. My questions are:

1. Since I don't have bass management, I've ruled out the PEQ3 Amp but are there any other qualitative differences between the newer PEQ3 vs the older PEQ or XLR amps?

2. Is it better to run 2 subs in chain (amp line-out->sub1 line in-sub1 line out -> sub2 line in configuration) or a stereo setup (amp Left line out -> Left Sub Left Line In and amp Right line out -> Right Sub Right Line In)

3. If a chain is the better option then can I run unbalanced RCA into the first sub and run an XLR cable to the 2nd sub assuming they were on opposite sides of each other and cable distance would be an issue.

Thanks,

Chris