Preamp shopping for pass ACA monoblocks

Have two pass amp camp stereo amps (32wpc each) running as monoblocks with Tekton pendragons and I’m in the market for a good preamp. Have a cheap aiyima tube preamp presently. Any ideas or suggestions?

thank you!
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No mods, they are stereo bridged for mono use. Budget is not a lot more than $1000, less if i can make it happen.
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Is the b1 a diy build or can I buy a completed unit?  What about other preamps with a no gain stage? Schiit freya+ for example?
Akitika PR-101 preamp is fine and nice.
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I built the Bottlehead Smash and use it with my Pass ACA monos. Nice match. Their 300B preamp is said to be even better. 
d2girls, Have you built the Akitika PR101? I built the first amp and was very happy with it, Ive been thinking of giving the preamp a try. 
Akitika GT-101 review