Bridged amps

gfry Is there any advantage to using two bridged power amps

Yes here are the reasons.
https://forum.audiogon.com/posts/1926175

If you have two amp the same your far better off vertically bi-amping
https://www.av2day.com/wp-content/uploads/2014/05/biamp2.jpg

If dissimilar amps are use they need to be horizontally bi-amped with a simple passive ($49 Schiit Sys) volume on the input of the louder amp so both amp can be level matched.
https://www.av2day.com/wp-content/uploads/2014/05/biamp1.jpg

Cheers George

Sorry first word in the above post, should be NO!!! not yes

Granted what I'm relating to you is regards to bridged integrated amplifiers but it may apply.  I had a single Pathos Classic MK III and it sounded quite good but I read that a bridged pair took a sonic leap forward and the single amp really was on the weak side at 70w/channel.  I bought another and bridged accordingly and indeed, most of the sonics improved.  Immediacy was the most obvious as sounds were now more forward and easily discerned.  Dynamics improved as well.  My only complaint was that I felt the soundstage wasn't as deep.  The fellow that turned me onto bridging the Pathos amps suggested I try the same with the Cambridge Audio 840W.  I did have this amp but never got around to bridging them but heard the improvement was also obvious.   The answer to your question may well depend on the amps.

I just had a pair NAD 2155 amps in the garage and a friend gave me a NAD 1155 pre amp. So I thought I'd use each amp in bridged mode.

Thanks for your help lcherepkai

Just get a better "stereo amp" with the wattage you need without having to compromise it by bridging it.
And if you can't afford that kind of amp for your speakers that may need it, get rid of the speakers.

Cheers George