Upgrade advice: Conrad Johnson MF-2500a ?

HI. I am considering upgrading my amp-I am currently using a PS Audio HCA-2. I was impressed with the C-J MF-2200 when I used to own one, and was considering buying an MF-2500a. It seems to be very well regarded for the price. I have also heard good things about the Musical Fidelity 308cr.

Any opinions on these two amps? Would either be an upgrade over the HCA-2? My amp evolution has been: C-J MF-2200 (nice, but lacking detail and frequency extremes), McCormack DNA-125 (better bass, a bit more detail, easy to listen to), PS Audio HCA-2 (best so far, much more detailed and even a bit more "tubelike" then the others). There are no decent dealers in the area, so I will be buying used off of A-gon.

The reason I am thinking of upgrading: each time I upgraded the amp, there was a noticeable difference in sound quality (most so with the HCA-2). I would like to keep that streak alive!

My preamp is the EE Minimax w/upgraded caps, and speakers are Soliloquy 6.3's. CDP is the Opera Reference 2.2. I listen mostly to jazz and orchestra.