The answer is definitely maybe. Yes, your Danes lower sensitivity is an issue. If 3.4 ohms is their low point, that's not too much of a concern since most tube amps have 4 ohm taps as well as 8 ohm taps. Bigger questions are about the size of the room and how loud you like to listen. Remember, 86 db means that you will generate a SPL of 86 db at 1 meter with 1 watt of power. That means 10 watts will generate 96 db. 10 db = twice as loud, so 96 db is twice as loud as 86 db. However, the farther you are (from 1 meter) from the speakers, and or the bigger the room, that 86 db rating will drop. How lively (reflective) the room is will also factor into the equation.
So the only real answer is to try for yourself. See if you can borrow a tube amp for demo. Do you have any local audiophile friends or dealers who may be able to assist you here?
My gut feel is that you should be fine, unless you are in a very large room and/or listen at very high levels. Most of us don't use nearly as much power as we think we do. You are probably using less than 10 watts of your 350 watt amp now.
So the only real answer is to try for yourself. See if you can borrow a tube amp for demo. Do you have any local audiophile friends or dealers who may be able to assist you here?
My gut feel is that you should be fine, unless you are in a very large room and/or listen at very high levels. Most of us don't use nearly as much power as we think we do. You are probably using less than 10 watts of your 350 watt amp now.