Tube preamp for Pass Labs x150.5 Amp

I currently have a AES AE-3 DJH Preamplifier linking together my Metrum Hex DAC and Pass Labs x150.5 Amp. The Pass is such a neutral/warm amp, that the AES tube preamp is making the total sound too warm in my opinion. I'm thinking of replacing the preamp with something not as warm, but would still like to stay with a tube pre. What would you recammend as a tube pre that could still have that tube sound, but not as warm? I'd like to keep it under 2K used or new, and am considering the Red wine isabella. thoughts?