There is another great option which unfortunately doesn't work with your 4 ohm Dali speakers, but might be helpful to others with 8 ohm speaker systems. We have set up two of the REF110's in balanced bridged mode (also sometimes called push-pull). In this configuration your double the slew rate and cut the rise time in half while doubling power. You also retain the character of the REF110 amps.
A side benefit is that if one of your amps ever has a tube failure or is down for any reason, you have a second 110 that can run your whole system.
A side benefit is that if one of your amps ever has a tube failure or is down for any reason, you have a second 110 that can run your whole system.