Why does bi-amping speakers sound better?

@viggen900 
I feel your pain, but an old house has more character than a new one.
Hopefully, eventually, you will get to the wiring. And, as you said, it should be an easy upgrade.
 If code permits, and you can run new wiring without needing conduit, it should be a slam/dunk. I posted a thread a couple months ago regarding a whole house surge protector. If you do get around to re-wiring, I encourage you to consider adding one. They don't cost much and can give you some piece of mind, as being one layer of protection.
B

Vig, just saw this thread.  One question for you.  Have you spoken to your dealer about your situation?  It sounds to me that for the money, you may want to consider newer speakers first rather than sink money into new electronics.  Eventually doing the electrical will help, but with the new technology, speakers have come a long long way. 

I have a pair of Vandersteen Quartro's being shipped this week.  I upgraded to them in order to get an active sub built in.  The main amp will now only be responsible for sound from 100hz on up, so it frees it up greatly and will improve it's sound dynamically etc... Yes, I also bi wire.  Some designers don't are about bi wire.  This is why I try ti personally purchase 'system's' and not just randomly get a well reviewed amp, a well reviewed speaker and and a well reviewed DAC or TT.  

What is your budget?  If you sold your speakers, what would your budget be then?  It's just a thought.  Heck, my Ayre AX5/Twenty like all Ayre products has filtering built right into the unit.  I plug directly into the wall and it sounds it's best.  From the amps you mention, it all seems to be about the largest number of watts you can get, however the majority of great speakers don't need that much to sound good.  JMHO

I have Avantgarde Duo-Omega gen II, 16 ohm. I am using the Ultra-linear OTL, one stereo amplifier for each channel, full range, so no electronic crossover in the signal path. The left and right inputs on each amp is combined with a little internal wiring change to avoid using a Y connector. The right channel output goes to the bass and tweeter. The left channel goes to the midrange horn. I did it this way because the midrange horn has no crossover, so the voice coil is connected directly to the amplifier. The sound is much better than running the amps in monoblock mode with double the power driving all the speakers. In the configuration I have, the output is 20 watts per channel. With the speakers have a sensitivity of 107db, there is plenty of power. This is the reference system in my home, where I test our cable designs. 

intersting.  Thanks for sharing.  There are so many ways to set things up.  It all comes down to personal tastes (as it always does) and how speakers are designed.  This is why I always ask whatever designer made my speakers, what they recommend and go from there.  

Heck, I need an external crossover for my Vandy's and I had Ayre build it into my integrated amp so I could cut out some extra connections, plus they used premium parts as does Vandersteen, so I didn't lose anything.  

A long time ago I used a bi-amp setup with two Rega amps into a pair of Proac D-28.  The improvement over using one amp was very noticeable-night and day.  When I sold the amps, I talked someone into buying them both and try the bi-amping and that person fully agreed that the bi-amping made a big difference. 

I forget which way the bi-amp sounded better but I do remember trying it both ways; with one amp powering the left speaker and the other the right, and with one amp powering the left and right woofers, and the other amp powering the left and right tweeters.  But I do remember that while it was close there was an improvement doing it one way over the other.  I think that is worth experimenting with both methods so you can find what works best. 

I did not test to see if one more expensive amp would have sounded better than the two separate amps.  But my guess is that while a better amp sounds a bit better than one that is half the price, I just don't see the improvement being as dramatic as what I heard from bi-amping.  So I am a believer in bi-amping based on my limited tests.