The main consideration with 4 ohm speakers is current capability in the amplifier. This speaker impedance is considered a relatively "difficult" load compared to the average 8 ohm speaker, so this must be taken into consideration when looking for a power amp. I would certainly not recommend a receiver to drive 4 ohm speakers - a seperate amplifer is the only reliable way to drive them.

The Outlaw amps certainly have a good reputation for sound quality, and the current delivery of the 200 should be a good match for your speakers. Honestly, the only way to absolutely, positively achieve a "warm" sound character is with tubes, but I would cerainly not recommend a tube amp for driving any 4 ohm speaker.

I would try the 200 out. The build and electronic robustness of the construction is extremely high with the Outlaw amps, as it is with the 950 preamp.