Two Amplifiers Connected in Parallel?

Provided my preamp (receiver) can power two identical 2CH amplifiers, what are the advantages (if any) of connecting the two in parallel, one amp driving tweeters, the other driving mid/bass drivers?

Amplifier (Rega Maia) has a L/R link output in addition to L/R input. Preamp (Pioneer Elite VSX-32 receiver) has single L and R outputs. Speakers are Spendor 7/1.
You are going to get a variety of answers on this; what you are describing is horizontal bi amping. I have always liked vertical bi amping where each amp drives both sections of each speaker but others like it your way. Besides the extra power it is generally thought that bi amping provided better definition and increases transparency. It also increases complexity and can sound worse if not done carefully. I am not familiar with your gear, make sure that all outputs are controlled by the volume control, otherwise one will get full output at all times. If you have only a single output you can use a Y plug or other adapters, I have had ones custom made by cable companies in the past.
"Besides the extra power it is generally thought that bi amping provided better definition and increases transparency."

I would add this is far from a universal opinion.

if you search the archives on "biamping" (may want to try various spellings (eg "bi-amping"), you will find a wealth of discussion to answer any questions you have.

I agree with the responses above. I have tried vertical and horizontal biamping with mixed results. Results in my experience are highly dependent on the equipment you're using and the speakers you're driving, and can range from awful to very good.
If you do not use an electronic crossover, this approach has limited usefulness. It works better with transistors than it does with tubes though, as most speaker crossovers are high impedance when they are blocking the unwanted frequencies. This causes a transistor amp to make less power. It may not reduce the power of a tube amp all that much.

If you use an electronic crossover, the introduction of the crossover itself will have an audible artifact. How much has to do with the design, but no crossover will be completely transparent or neutral. In addition, most speakers have nuances of driver behavior which most electronic crossovers don't take into account.

So it can be tricky! My advice is to try it but be careful- the top amplifier outputs cannot in any way have connections to the bottom amplifier (for example- through the speaker's passive crossover), else you could damage something.
I tried it last year .My set up was Aerial acoustics 10T with Rogue Zeus 200W driving bass on both channels and Rogue M150's 150W monoblocks on mids/highs with Rogue Magnum 99 pre dual outputs.I REMOVED the bridging straps at the back of the Aerials.I used this set-up for about 2 months and then tried then Mark Levinson 27.5 connected on the same speakers and I prefer the sound this way better.I am planking in the future to get an active crossover like the Bryston 10B and try it as Atmasphere describes.I was told that the Aerials have a well designed crossover specific to the design so I am sceptical if an external crossover will achieve better results.Your milage may vary,but try and see for yourself.
Thanks everyone for the replies. Comments so far leave me on the fence regarding this. I don't have much experience in this sort of thing but intuitively, somewhat makes sense.

If I do try this, here is will do:

Equipment: Pioneer Elite VSX-32 Preamp/Receiver, Two Rega Maia amps, R & L Spendor SP7/1 speakers

Single line L and R outputs from the preamp and connect to L and R inputs on amp1. Use amp1 L and R link outputs and connect to amp2 L and R inputs. This is the parallel connection.

Amp1 R speaker outputs to R speaker tweeter, amp1 L speaker outputs to L speaker tweeter.

Amp2 R speaker outputs to R speaker mid/bass, amp2 L speaker outputs to L speaker mid/bass.

Make sense?
Biamping is a perennial topic, and it is usally asked by folks who know very little about it, except it 'sound' (inthier hhead at least) exciting and sophisticated. Biamping is neither of those things.
If you are going to BUY two amps, your are ALWAYS better off getting one better amp.
Ony if you happen to have two amps laying around, and want to play around, then yeah, try it.
And forst off you would divid a 'three way' speaker system by woofer on one, and the combined mid and treble on the other!
Treble portion of the output is miniscule!!
Say you are using 50 watts for the whole speaker, then 40+ of those watt is going to the bass, and 8 watts to the midrange, and less than 1 watt to the tweeter (on average).
Low frequencies use the majority of the power.
If you do a search about biamping, you can see that a few folks (who know what they are doing, get good results, the majority is almost as good to not as good as one better amp.
Save yourself the hassles and buy one good amp.
I am not familiar with the Spendors,so assuming that they are bi-wire capable,that is they provide TWO inputs at the back ,then remove the bridging straps.Your connection seems wright.
If you want go to youtube and search for "virtualdynamics" "QnA bi-amping" there you can find a 10 minute tutorial from Rick who explains it further.
Thanks again for all of the replies.

Elizabeth, I do fall into this group: "usally asked by folks who know very little about it, except it 'sound' (inthier hhead at least) exciting and sophisticated"

Yioryos -- Thanks for the virtualdynamics video on youtube. Most of the discussion involves vertical bi-amping but after viewing I'm not sure why vertical or horizontal bi-amping really should ever be considered. It seems that monoblock amps are the only consideration if using two amps in a 2CH set-up.

I've decided against the horizontal bi-amp idea.
Can the Rega Maia amps be bridged into mono? For example my Mark Levinson 27.5 was designed to be bridged and it says so in the manual ,it does require a special cable to complete the switch and of course a second ML 27.5 to be used to drive the other channel.A while back I looked for a used 9/10 or better condition ML 27.5 in Audiogon to buy,I wasn't satisfied with the condition of the ones I found,except one that was truly mint but priced very high and the seller was difficult so I passed,and I do regret it now.
All the other Rogue gear I used in my bi-amping set-up I own and have at home so I could play around.I am hoping to perhaps buy an external crossover such as the Bryston 10b (usually goes for $1000) and get same cabling for all connections and give it a second try.
Best regards
George - Thanks again. Not sure that the Maia can be bridged to mono, but I will try to find out. The manual does not mention bridging as an option, but I will contact Rega directly to be sure.
Please see this site.
George -- Thanks for providing the link. Very good information.