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!
sexychicken
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?
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