Any suggestions on coolest running monoblocks?

I am with Muralman1! I have the S-250 Signature Stereo driving Magnepans. At first I thought the regular Stereo is very very good but the Signature model makes it even better. At 1kVA per channel of torroidal transformer, it runs exceptionally cool.

cheers

Rowland 201 - retail $4700
H2o Signature Stereo - retail $2800 (I think)
H2o Monoblocks - retail $4000
Channel Islands - unsure of price
eAR - unsure of price
Spectron - unsure of price
Jjaz - unsure of price
Bel Canto's - unsure of price

Just about any digital or PWM amp out there will run without any noticable heat... your hand on the case will feel as if the unit is turned off.

There is much difference sonically between many out there. I personally have only compared the Rowland 201, 501 and H2o amplifiers with this technology... definately suggest a listen prior to purchase.

Look at acoustic reality 1001 monos,1000watts at 4 ohms.I like them they run cold,you can buy them straight from Denmark about 1700 a pair

I have the latest version of the Herron M150 monos. They are terrific amps and run cool. They won't wow anyone with their looks - chassis is very plain, black and small - but they are highly musical, powerful little guys. They are solid state, but they do retain many of the virtues of tube amps. There are rave reviews at Enjoy the Music. Used about 2400-2700.

Nanotweeter,

In my system, the D-100s were more "tube-like" in the midrange than the Nuforces. Being a long time tube amp lover, this was very important to me. In addition, I felt the D-100s had a tad more width at the back of the soundstage.

To use an analogy, the difference between the D-100s and the NuForces in my system was like the difference between Vinyl and SACD. Both offer a very hi-rez presentation, but they are different. I happen to favor a more "vinyl-like" audio presentation. YMMV.

Truth is either one of these amps would be right at home in any high end system. In fact, I'm holding onto the NuForces until my new speakers (DeVore Silverback Reference) arrive, just to confirm which amp has the best synergy.

Hope this helps.