I have M1.2 monoblocks and owned the Lamm LL2.1 Deluxe, then Musical Fidelity hybrid kW and now have an Audio Research Reference 5. Each move was a step in the right direction of improved transparency, attack and dynamics. The Ref 5 gives me the tube bloom and dimensionality with natural attack and dynamics. The Lamm was nice, but lacked transparency, obscured some musical detail, and I missed a remote control for volume.
So given your budget, you might try a used Ref 3. If you want to understand the sonic difference between the Ref 3 and Ref 5, read Jonathan Valin's review in TAS.
Good luck!