Using Eclipse TDs for surround sound.... Need advice for centre speaker

I've been happily running a pair of TD508iis with matching subwoofer in a 2.1 configuration, and recently purchased a Pioneer AV receiver to experiment with a centre channel. Currently, I am using a smaller TD307ii as a centre speaker. It's a little smaller (100hz vs 80hz roll off) but timbre is well matched and performance is very similar for vocal reproduction. However, since it's a single 6.5cm driver, I find it's not really suited to the task... Clarity and volume is fine (sofa is only 3 metres away), but it's missing fullness / prescence. The cheap philips centre speaker I have is better in this regard (minus fidelity) as it has two drivers. I am wondering if it's feasble to wire up an additional 8 ohm TD307ii to the centre channel also to mimmick the dual mids config usually found in centre speakers. My receiver can run 6-16ohm speakers so running them in serial should work? Either that, or I'm thinking a similar egg shaped centre speaker might work.... E.g Kef's HTC 3001 Any suggestions would be most welcome
 
Can you get another one ?
Or ideally match all 5 speakers......

Same speaker across the front sounds best to me and many others.

Fullness to me is bass, and for movies at 10' away, well, good luck.
You can cross at 200hz at the receiver, but then it would help having the sub somewhere between the 2 front speakers, not shoved off in a corner.
 
I already have another TD307ii here (they were bought as a pair). Another TD508 would be ideal but they are harder to find and discontinued, so finding a single one for sale is unlikely. I've read that wiring speakers in serial can be problematic, but since these are single/full range drivers with no crossover my hope is it will work OK.



The matching subwoofer does a fine job with bass duties and is crossed over at 100hz between the front speakers. I hear what you're saying though, upping the high pass filter may help? The low pass filter dials from 40hz up to 200hz so plenty of range, I'll give it a try.