preamp matching to poweramp


What does one need to take into consideration when matching an amp and preamp? The models I am currently looking at are the Opera Consonance M500S Signature 300B Monoblocks running at 18w and the Decware taboo running at 6w. I may have found a preamp for the Opera

http://cls.audiogon.com/cgi-bin/cls.pl?preatube&1141938743

but the decware is a bit of a question for me.

I gather you should try to keep with in the brand, but I need more inputs than decware preamp offers and I dont have money for 2 preamps.

Thanks.
someguy
You also would not want to pair an amp with a particularly sensitive input stage with a preamp that is very high gain -- you will have very little range on the volume control (9 O'Clock can be full-blast with bad mismatches). This happens, so beware.
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Some solid state amps are reputed to be sensitive to DC leakage from tube pre-amps. Some old pre's offered power outlets. While I don't suggest you use them (especially with an amp), they might have compatibility issues there. On the same track and this may sound silly, but you asked so; you might want to have both pieces work off of the same proper native power voltage or it might get a little tricky.