Water cooling might actually be pretty easy... assuming you can pin-point the best places to cool. Pretty much, if you could attach a 'super heatsink', preferably on the flat bottom side of the amp and out of view, where would be the best place for the heatsink to go?
...actually I guess with this idea:
http://www.newegg.com/Product/Produc...-050-_-Product
you could just use a thin copper shim/plate and attach it to one of the larger water blocks/heat sinks using the thermal adhesive to create a larger surface area. Maybe put a few of these modified water blocks w/ extra surface area in places under the amp that produce the most heat, and it'd probably work great actually.
Could use Artic Silver thermal compound adhesive to attach the heatsink(s)...
its supposed to hold very strong, of course w/ high temp too:
http://www.newegg.com/Product/Produc...82E16835100005
Most are small, for chipsets, but like above you could make the heat sink larger, and the liquid would still do a great job transfering the heat away (40x40mm, 50x50mm)
http://www.tigerdirect.com/applicati...057&CatId=1871
http://www.newegg.com/Product/Produc...-019-_-Product
Although a larger water block/heatsink like this would be excelent, if only the contact point was perfectly flat...
http://www.tigerdirect.com/applicati...8368&CatId=499
http://www.newegg.com/Product/Produc...-027-_-Product
This one actually seems plausible, multiple copper contact points are at the same level except for one that could easily be rasied up to the level of the others with a copper shim + thermal adhesive
http://www.newegg.com/Product/Produc...-108-_-Product
also, of course, like cooling a computer... I guess you could run lines for in and out flow into the amp and put the low profile ones straight on the chips that make the most heat... example: ones for mosfet:
http://www.newegg.com/Product/Produc...-024-_-Product
except I would be too concerned about a leak inside my amplifier!!! I guess the same goes w/ computers, but still....
and ya, plenty of stuff to choose from for the reservoir / pump / radiator.
one like this you could route to a more visible area and show off your liquid cooled system for your amps lol:
http://www.newegg.com/Product/Produc...-033-_-Product
http://www.newegg.com/Product/Produc...-108-_-Product
http://www.newegg.com/Product/Produc...-117-_-Product
Of course all of this seems a bit overboard and extremely expensive when a couple crossflow fans or even computer case fans w/ the air flow routed should work fine?
http://cgi.ebay.com/XScorpion-12-Vol...3286.m20.l1116
http://www.newegg.com/Product/Produc...-002-_-Product
Even tho the water cooling is expensive and overkill... I wonder if anyone has done it for a show car??