I own all three different series- ie. Connoisseur Series, new C-Series and new RC-Series. After my own personal experience I've come to believe, or realize, they are essentially three different design's with their own respective sound characteristics. Moreover, I believe, there may be some, mis-information, or confusion, regarding the new C-Series' expectations as opposed the their actual performance.
Four years ago I was using C-1's and C-3's with Yamaha receiver's (50W per/chan), primarily for 2-channel music. Both, the C-3's and C-1's, were very nice, mostly crisp and clean sounding, with good imaging, to put it simple- especially for bookshelf type models. I recieved several good comments while playing music in my house. My son now has all this equipment and is very happy with it (say's all his friends can't believe how good the speakers sound).
Three years later (2005) I purchased C-5's, a C-C1 center, an S8.3 sub, along with a Yamaha RX-V1500 reciever (120W X 7), through a liquidation sale. I thought the C-5's had very nice, clear, hi's, with good mid-range (much like the C-1's and C-3's), however, with un-believeably smooth, deep, bass response. My first experience using floorstanding tower's. 2-channel music sounded [even] nicer, with more full-range bass. Also, Home Theater surround was a whole new amazing experience, clean and explosive sounding, with very nice imaging.
I was totally impressed with the design form & function of the Connoisseur Series- unique front baffle design, magnetic grill fasteners, nice quality finish, excellent sound- great overall package for the price.
However, last fall (2005), I read the press announcement on the Energy web-site in regards to their releasing a complete new Energy C-Series product, it sounded very intriguing to me. The drivers consisted of fiberglass composite cones (actually fiberglass molded cones laminated to a poly-type rear layer for extra stiffness). While the tweeters are based on their popular Aluminum Hyperdrive dome design. Moreover, the Energy web-site stated- "the new C-Series is intended to replace both the XL Series and Connoisseur Series", and further went on to claim- "The C-Series C-500 is capable of greater extension, slam and impact than its C-5 predecessor, with less distortion and better articulation." I was completely excited and could'nt wait to try them. Pricing was even better than the Connoisseur Series.
So I purchased new C-Series speakers (C-300 front's, C-C100 center, C-200 rears) in February (2006), along with a (new) Yamaha RX-V1600 receiver (120W X 7). After burning-in over 100 hours I was fairly impressed with the system, Home Theater surround was excellent, clean and explosive sounding, overall, for both DVD's and digital cable. However, 2-channel audio, in "PURE" mode, was not as clean sounding (as the Connoisseur series) playing through the C-300 fronts, I thought. The hi's were more "veiled" or "muffled", as if the tweeters were different. Although, mid-range and bass was very good. I experienced the same characteristic later switching the C-200's to the front, very good mid-range, but not as clear hi's (wish I could have tested C-3's at same time). Later, I bi-amped the C-300 front's and, I thought, they sounded better overall- more open mid-range, with deep, smooth, bass response (not bad for a single 6.5in woofer, 2-way, floorstander). After a few months I bought an NAD C272 amp (150W X 2) to power my C-300 fronts (using Yamaha RX-V1600 as pre-pro) and they sounded even better, slightly cleaner overall sound, with even nicer bass response.
Overall, I thought the new C-Series are good, and more than worth the price. Very good design form & function- beautiful laquer finish on front baffle, seamless outer vinyl laminate, decent grills (no magnets though), good accessories (spikes, etc.,..). Good sound, maybe not as clean-sounding as Connoisseur Series? However, mid-range and bass as good (I thought), with excellent imaging/soundstage. Home Theater surround performance is very (surprisingly) good, while 2-channel audio characteristic's may vary depending on power source.
In May (2006) I swapped my (new) C-Series for the new RC-Series (RC-30 fronts, RC-LCR center, RC-Mini rears), and I'm beyond impressed with the overall design & function, definitely a step above the Connoisseur Series & new C-Series in sound quality and fabrication. Much better overall clarity and transparency. Clean hi's, good mid-range, with deep, smooth, bass response. Home Theater surround, and multi-channel music, is excellent! 2-channel audio is excellent!
RC-Series feature magnetic fasteners on grills, nice accessories (spikes, etc.,...), beautifully laminated (real wood) veneers, kevlar cones, all for an excellent price! I'm very content now with my system.
I would definitely prefer the RC-Series out of the three series, and would'nt be so "hung-up" with finding older Connoisseur Series models. The new C-Series definitely make for a great first-time Home Theater on a budget.