Bi amping my ML SL3 speakers

+1 on suggestions to use one good amp and bi-wire the speakers. However…
Few things to consider here -

1. The ML panels present more challenges to the amplifier than the woofers do. This is because the impedance on the panels can dip below 2ohms. I do not think your rotel is a good match for these speakers and bi-wiring is unlikely to improve things much. 

2. When you say your woofers distort, what kind of distortion are you talking about? What does it sound like? Could have nothing to do with amplifier and bi-wiring is unlikely to resolve it. 

Bi-wiring or using another amp will not solve that issue. The SL3 are old. Even new they never felt comfortable playing at concert levels. It’s possible something is wrong with woofers so you can look into it. Give ML customer service a call. 

What I’m suggesting though as a better path forward instead of spending on speaker cables and amplifiers, upgrade the speakers. Anything Montis or newer should be a big improvement over the old SL3 if you want to stay with ML. 
 

👍

I looked up that Rotel amp. It’s ok. Should be fine but what I suggested about moving to a newer model MLs (if you like the sound) has several benefits-

1. Newer design Montis (I had those), Summit, etc. have powered woofer. I drove the Montis with Rogue ST100 and later with Pass XA-30.8 So they’re easier to drive

2. Better, more seamless woofer/panel integration.

3. Newer/fresher panels - these things age. They also accumulate dust. Both the age and accumulation of dust impact the way they sound. You can vacuum the panels or even wash them in the shower (panels only).

After owning Aries I and Montis, I eventually moved on. But the MLs are great speakers without a doubt. 

Quantity is much less important than quality here when talking watts. Don’t get hung up on amplifier power.

If you want to make what you have work, disassemble the SL3, check woofers, make sure all the screws are tightened, vacuum or wash the panels. Also check the rear of the woofer cabinet. Make sure everything is tight and nothing rattles. Reassemble and check how they sound. If still issues, sell the SL3 and move on.