I had excellent bass from my M150s powering my Alon Vs. Probably a more benign LF load than your speakers.
I liked the Spectron Musician II amp I tried but I personally much preferred the sound of the Herron amps. I didn't try keith's newer amps, the M1s on my rig.
There is definitely a synergy with Herron pre and amps. If you like your M150s in all other erspects, I would try to bi-amp.
I'd also try to get the newest Herron pre if you can.
I liked the Spectron Musician II amp I tried but I personally much preferred the sound of the Herron amps. I didn't try keith's newer amps, the M1s on my rig.
There is definitely a synergy with Herron pre and amps. If you like your M150s in all other erspects, I would try to bi-amp.
I'd also try to get the newest Herron pre if you can.