Anyone recommend a neutral tube amp?


I've been wanting to move to tubes for some time now. Lately I've changed most of my equipment. I now have a Rega Saturn CDP and some very revealing Opera Callas monitors. My amp is the Sim Moon 5.3 integrated. I like the neutral character of the amp, it simply takes on the characteristics of whatever is being played through it. Can anyone name a tube amp that is similarly neutral, that won't color the sound of the CDP?
rfprice
Atma-Sphere and VAC are very transparent (neutral). I believe most tube amps manufactured today are relatively neutral. It's damn hard to find a tube amp with the stereotypical rolled-off and bloomy sound some people associate with tube amps.
Tube amp, even it is OTL, has much higher output impedance which when interacts with speaker can cause multiple db swing in the speaker's frequency response. If you really want a neutral amp, don't buy tube.