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
Thanks for all the responses thusfar. Tim, you're right to be concerned about the 87 db on the speakers. I've found some amps, such as the Mac 275, to be underpowered with them. I once heard the ARC 55 watt integrated and I understand what you mean by "aluminized." However oddly, that 55 watt amp drove the speakers very well, unlike the 75 watt Mac. I've heard the Atma-Sphere talked up often. I'll have to look around for that. Unfortunately the dealers in my area don't stock much tube gear.
CAT JL2/Signature.

If you're in the market, compare the top 5 votes, and if I was a betting man....

It does depend on what you value as a listener and then of course room/system synergy.
is it possible that the intent is not to find a pefectly neutral tube amp, which in fact doesn't exist, but one providing balanced frequency response and sufficient resolution to satisfy most audiophiles ?

is the presence of coloration so objectionable that one would try to attain the unattainable ?