Speaker wattage ratings are generally more a limit before damage type of information, not that speakers "need" it or will even sound good at those power levels. Too bad your Onkyo doesn't have a full set of pre-outs, then you could just use that with any amp(s) you wanted to add. I would maybe buy an amp from Emotiva, but not their electronics generally. Can you still return the Onkyo 6100? I generally use avrs with a full set of pre-outs so as to have amp flexibility.
I've been happy with my various Crown XLS amps (have four 1500s and a 2502). I use them for diy sub duties mostly but currently running some JBLs on the 2502 at the moment....I have several systems, tho (mostly multich). I had CVs once upon a time, but didn't care for them all that much but they were smaller speakers than the XLS215s. More likely your XLS215s are 4 ohm; they're nominally rated at 6 ohm rather than 8, too. Looking at the sensitivity spec of 95 dB for 1w/1m seems a bit high, I think CV overstates it (as does Klipsch). Sensitivity is a better indication of the relationship of amp power for a speaker in any case. Try this
http://www.hometheaterengineering.com/splcalculator.html
Not sure what you mean by doing something else with the E715s, altho for 2ch stereo I generally prefer just two speakers; if I used the E715s they'd more likely be in a surround mode rather than 2ch.
Haven't used dedicated cd player in years....used dvd players until bluray came along and now use a few bluray players for optical discs (the more types of disc the better IMO, and there are a fair number of quad SACD discs if you have certain bluray players that can play that format).
