Luna,
The other thing to consider is hybrid-design power amps (tube input/driver stage and SS output stage). Here are some to consider:
http://www.audioadvisor.com/prodinfo.asp?number=1VISPT800http://www.moscode.com/moscode_amplifiers.htm#topThe Vincent STP-800 was a TAS 2008 Product of the year and can be bought at Audio Advisor that has a 30-day return policy as long as you keep the product in "like new" condition and return it in original packaging.
The Moscode 402 power amp recently was reviewed by Wes Philips at Stereophile in the Sept 2009 issue (
http://stereophile.com/solidpoweramps/moscode_402au_power_amplifier/) and can be bought direct from the manufacturer with a 33 and 1/3 day (i am not joking about that) in-home audition trial period.
The other option is to get a tube hybrid integrated amp of which there are many options with 200+ wpc and that allows you to simplify your system (fewer components and cabling). I have no idea what the above units sound like but at least these two options can give you the ability to audition and if they don't meld well with the 3.7 or the WP8 then you can at least return them. Just a thought.