you should look seriously at the KR P-135. It is a 45 based preamp and throws out a huge sound-stage with tons of dynamics. This is the review from Positive Feedback.
https://positive-feedback.com/reviews/hardware-reviews/kr-audio-p-135-preamplifier/
Full disclosure, I am a KR dealer but this is a pretty special preamp. I would also suggest you look at the Art Audio Conductor but that is a bit above the price range you have listed. It is highly customizable with switchable gain and it has an amazing headphone amp.
https://positive-feedback.com/reviews/hardware-reviews/kr-audio-p-135-preamplifier/
Full disclosure, I am a KR dealer but this is a pretty special preamp. I would also suggest you look at the Art Audio Conductor but that is a bit above the price range you have listed. It is highly customizable with switchable gain and it has an amazing headphone amp.