Does any one have experience with a high-end amp switch or the Luxman AS-55

I have used a Luxman AS-55.  It works great although I prefer the AS-50R remote model for comparing speakers because I don't have to get up off my butt to do an A/B comparison.

Audio by Van Alstine also makes a very good comparator.  It's probably the best of the bunch but the Luxmans have worked great for me.  Good sound and no damaged gear.

$550? Swap bananas. Or if you want to be very cool get a high current 4 pole relay with a 25 volt coil, a 25 volt power supply and a hand held toggle switch. Cost you less than 100 bucks. Wire it all up in a metal or plastic box and change speakers from your seat. 

It looks like that switch is designed for a single amplifier to switch between multiple speakers - I'm not sure it can be used to switch multiple amplifiers into one pair of speakers.

Thanks @br3098 and @cleeds 

The unit's documentation shows it can be used to switch between amps.

@br3098 I appreciate the heads-up on the remote version. I couldn't find the Van Alstine product you described on their website -- is it a custom unit?

Fwiw, I also heard back from Luxman Global who indicated that the switch was indeed good for the L-509x (what else were they going to say!), and that I should use good jumpers/cables.

The AS-55 and AS-50R can absolutely be used to switch one amp source to up to three sets of speakers or three amp sources a single set of speakers.  Just remember that it's a switch designed for speaker output only.  It's a brilliant design and is done well.  I don't think I could build myself with similar quality for what Luxman charges for these devices.

Cables?  I would just use your standard brand of speaker cables for the longer runs.  The short jumper pair to the single amp (or speaker) can be almost anything.  I prefer inexpensive silvered copper wire jumpers but use whatever you like.  If they are under 24" you could almost use coat hanger wire.  Almost...

Here's the link to the Van Alstine device: https://avahifi.com/products/abx-switch-comparator