What is the best premp for Atma-Sphere MA-1 3.3 amp?

thank you all for your comments. If MP-3 is 90% of MP-1, I doubt my ears can tell the difference. Then the question is, are you comparing version .3's? Or is there not that much difference between MK3 vs. MK3.3?

@chungjh check out Audioasylum trader there's a sealed MP3 mk3.3 for sale. 

@OP, 
I PM'd you, but didn't indicate the build model.
I own the 3.3 version MP-3.
Also, when I called Atma to inquire about upgrading the MP-3, he said the 3.3 was an entirely different build from earlier models, and to upgrade an earlier model would cost a significant sum. You can see the prices on Atma-Sphere's website.
BTW, one of the reasons you find so many satisfied Atma customers is that you are only a phone call away from help, should you encounter an issue. Most likely it will be Ralph answering the phone, and most likely it won't be the Atma causing the problem- believe me, I know.
Bob

Bob

I agree with you about Ralph. He was so patient with me explaining his circuitry and philosophy. I have no doubt that their quality and service is as good as anyone.

I listen to music via MP-1 and a pair of MA-1 amps. Sounds divine with a pair of 

of Sound Lab Ultimates U1-PX (Ultimate 745).