KEF 107 Amplification:
Since purchasing my 107s back in 2015, I've connected a number of amps to them in search of the sound I was looking for. Namely, a McCormmack DNA 0.5, Conrad-Johnson MF 2250, Jeff Rowland Model 2 (which I adore), and most recently a Pass Labs XA30.5. I thought the Rowland Model 2 would be my last amp purchase because it does everything right in my system. I still have it and am on the fence about keeping it because I know it'll be hard to find another. I may install it in my office system.
The Pass XA30.5 had been on my radar a while, but I always thought it would have a hard time driving the 107s with its rated 30 class A watts, so I kept passing up on listings until I saw one at a price I couldn't refuse. I'm really amazed at how well this amp pairs with the 107s. It's more forward in presentation than the Rowland, and offers a bit more dynamic range. The sound stage depth on good recordings and well engineered SACDs is incredible. One area that the Pass isn't quite up to the level of the Rowland is in bass clarity, but I've found this is easily tamed with the Kube by setting the Q to it's most overdamped setting, and dialing back the level a notch or two. Overall, I'm thrilled with both the Rowland and the Pass, and just wanted to let other 107 owners know that the XA30.5 offers plenty of power to drive the 107s. I believe the constant 4Ohm load and relative efficiency of the 107 help make this a wonderful pair.
Wow, never would have thought 30 watts would do much for the KEF's. I have a Monarchy SM-70 which I think is also 20-30 watts (also class A). Hooked it up to the KEF's very briefly and did not really push them at all, but didn't sound like enough juice to me. But again it was a very temporary thing, like minutes. Maybe I'll have to try again.
You have tried a lot of the amps I was going to try! We must have been reading some of the same "recommendations." I was going to try the McCormack and Rowland. Also thought about trying some bigger Monarchy or other Class A amps, or an Audire Forte. I've pretty much only used an Emotiva UPA-200 on mine. Sounds fine, but I always wonder if I could do better. Just hasn't been in the budget lately.