Stick with.. KMA-100'sMKII or go for KMA-160's ???

I made that exact switch. I was using the KMA 100s as the bass in a bi-amped system and moved up to the 160s. I didn't need more power, but the 100s are not terribly stable down below 30 Hz. Also, I hated the fan noise from the 100s. Additionally, the 100 is less reliable due to the way it is cooled. The 160s definitely have more punch and control on the bottom end. While I haven't used them on the top end, they should actually sound a little better. Most of the older Krell amps improved over time on the top end until they went to the plateau biasing. These really did not sound as good on the top end--but that came after the 160s.

I'd agree with Abstract 7; in addition, I'd say if you can get MDA 300s, they'd be even better, as they were sweeter and smoother on top than the KMA 160s with more power and bass control.

The only downside - more heat and greater AC line demands.

The KMA 160's draw more current from the AC supply. If you're close to maximum now with the 100's you might pop breakers with the 160's.

Remeber, the 100's and 160's draw lots of current from the AC line at idle since they are class A amps.

I too made the same upgrade with my Thiel CS-3.6's many years ago. I was very pleased with the change over to the KMA-160's especially in the imaging department? Don't know how or why but the sound opened way up and the KMA-160's never ran out of gas. Bass control also stepped up a notch adding that last bit of detail to moving bass lines. They were much more quiet than the fan cooled models / I'm sorry I let these go!!!!